Water & Medication Guide for Travelers to China: Safety, Hardness & Drug Interactions

Is Tap Water Safe to Drink in China?

Tap water safety in China varies significantly by region and urban development level. According to the WHO and China's Ministry of Ecology and Environment, urban tap water in major cities (Beijing, Shanghai, Guangzhou, Chengdu) generally meets the national standards (GB 5749-2022) and is microbiologically acceptable for direct consumption by the local population. However, the CDC and most international travel health organizations recommend that travelers, particularly those with compromised immune systems or unaccustomed digestive microbiomes, avoid drinking tap water directly.

Official Standards and Reality

China's national drinking water standard (GB 5749-2022) sets safety thresholds for:

• Bacterial contaminants (E. coli, total coliforms)
• Chemical residues (heavy metals, pesticides)
• Physical parameters (turbidity, color, odor)

However, distribution infrastructure challenges persist:

• Aging pipes in older urban districts may introduce contamination during transport
• Rural areas often lack consistent treatment standards
• Water quality can fluctuate seasonally, especially post-flooding
• Biofilm accumulation in older piping systems may harbor bacteria

Pharmacist's note: While local residents have developed tolerance to regional microbial profiles, travelers' intestinal flora have not. Even "safe" tap water can trigger travelers' diarrhea due to unfamiliar bacterial strains. This is not necessarily a safety failure but a microbiological mismatch. The additional risk: diarrhea impairs medication absorption for 12–24 hours post-symptom onset.

Regional Variation

Region	Safety Assessment	Notes
Tier 1 Cities (Beijing, Shanghai, Guangzhou)	Acceptable for locals; caution for travelers	Modern treatment plants, but aging distribution networks
Tier 2 Cities (Chengdu, Xi'an, Wuhan)	Variable; not recommended for travelers	Inconsistent pipe maintenance
Rural/Remote Areas	Not recommended	Limited treatment infrastructure
Tourist Hotels (5-star)	Generally safe	Private filtration systems common

Recommendation: Travelers should purchase bottled water, use hotel-provided boiled water, or carry portable water filtration devices (e.g., LifeStraw, Sawyer filters rated for 0.1 µm bacterial removal).

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Hard or Soft? China's Water Mineral Profile

China's water hardness is highly variable, influenced by regional geology. Northern China (Beijing, Tianjin, Shanxi) experiences hard to very hard water, while southern regions (Guangzhou, Kunming) tend toward softer water. Hardness is typically expressed in mg/L CaCO₃ equivalent or °dH (German degrees of hardness).

National Hardness Ranges

• Beijing & Northern Cities: 250–400 mg/L CaCO₃ (very hard; ~14–22 °dH)
• Shanghai & Eastern Cities: 150–250 mg/L CaCO₃ (hard; ~8–14 °dH)
• Guangzhou & Southern Cities: 80–150 mg/L CaCO₃ (moderately hard; ~4–8 °dH)
• Kunming & High-Altitude Areas: 50–100 mg/L CaCO₃ (soft to moderately hard; ~3–6 °dH)

Mineral Composition

Hard water in China is primarily composed of:

• Calcium (Ca²⁺): 80–160 mg/L in northern regions
• Magnesium (Mg²⁺): 20–50 mg/L
• Bicarbonate (HCO₃⁻): 200–400 mg/L
• Sulfate (SO₄²⁻): 50–150 mg/L in industrial areas

Health and Practical Implications

For General Health: Hard water is not inherently dangerous and may provide bioavailable calcium and magnesium. However, it causes:

• Scale buildup in kettles and appliances
• Reduced soap effectiveness
• Potential mineral deposits on teeth and skin

Pharmacist's critical concern: Hard water's high calcium and magnesium content creates chelation complexes with certain medications, reducing their bioavailability and therapeutic efficacy.

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Medications That Need Caution (Pharmacist's Perspective)

High-Risk Drug Classes in Hard Water

1. Tetracyclines (e.g., doxycycline, tetracycline)

Mechanism: Calcium and magnesium in hard water bind to tetracyclines in the gastrointestinal tract, forming insoluble chelate complexes that prevent absorption.

Clinical Impact:

• Bioavailability reduced by 40–60%
• Therapeutic failure for infections (acne, respiratory tract infections, Lyme disease prophylaxis)
• Onset of resistance if underdosed

Recommendation: Take tetracyclines with distilled water, boiled water from a known source, or bottled water at least 2 hours before or 6 hours after consuming hard water or calcium/magnesium supplements. Do NOT take with meals containing dairy.

Why travelers care: Doxycycline is commonly prescribed for malaria prophylaxis in Southeast Asia and Lyme disease prevention. If traveling onward from China to malaria-endemic regions (Southeast Asia, parts of Yunnan), chelation in hard water could compromise prophylaxis.

2. Bisphosphonates (e.g., alendronate, risedronate)

Mechanism: Calcium, magnesium, and iron form insoluble complexes with bisphosphonates, impairing absorption by up to 90%.

Clinical Impact:

• Complete therapeutic failure for osteoporosis prevention
• Increased fracture risk in susceptible patients
• Prolonged immobility during travel amplifies fracture risk

Recommendation: Take bisphosphonates with plain distilled water 30 minutes before food or water (no hard water, coffee, tea, or juice). If traveling and taking bisphosphonates, carry bottled distilled water or request hotel staff to provide boiled, cooled distilled water.

Why travelers care: Postmenopausal women and older adults on long-term bisphosphonate therapy are at higher fracture risk if their medication is chelated during travel.

3. Fluoroquinolones (e.g., ciprofloxacin, levofloxacin)

Mechanism: Similar chelation as tetracyclines; calcium and magnesium reduce bioavailability by 20–50%.

Clinical Impact:

• Reduced efficacy for urinary tract infections, respiratory infections, and traveler's diarrhea
• Prolonged infection duration
• Potential resistance emergence

Recommendation: Take 2–4 hours apart from hard water and calcium/magnesium supplements. Prefer distilled or bottled water.

4. Iron Supplements (ferrous sulfate, ferrous gluconate)

Mechanism: Calcium, magnesium, and phosphate inhibit iron absorption.

Clinical Impact:

• Worsening anemia in pregnant travelers or those with iron deficiency
• Reduced energy and increased infection risk

Recommendation: Take with vitamin C (e.g., orange juice) and distilled water, away from hard water and coffee/tea (which contain tannins that also inhibit iron absorption).

5. High Sodium Content in Some Mineral Waters

Risk: Northern China's hard water may contain 50–150 mg/L sodium (local water authority reports). Pre-packaged mineral water may exceed 200 mg/L sodium.

Clinical Impact:

• Hypertensive patients may experience blood pressure elevation with prolonged consumption
• Edema risk in patients with heart failure or renal disease
• Fluid retention in pregnant women

Recommendation: Hypertensive patients should check mineral water labels for sodium content (see next section). If sodium exceeds 100 mg/L, limit consumption and prioritize distilled or low-sodium bottled water.

Pharmacist's note: Medications are most vulnerable to chelation when taken on an empty stomach with hard water. Taking medications with food (except dairy) or with distilled water significantly reduces chelation risk. If you must take a tetracycline, bisphosphonate, or fluoroquinolone during travel in China, use bottled water or boiled-then-cooled distilled water from your hotel. Request "distilled water" (蒸馏水, zhēngliú shuǐ) explicitly if unsure.

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Leading Mineral Water Brands in China

Major Brands and Mineral Content

Mineral water labels in China display hardness in mg/L CaCO₃ equivalent or occasionally as TDS (Total Dissolved Solids) in mg/L. Below are the most widely available brands with their hardness profiles, where to find this information on labels, and availability.

Brand	Hardness (mg/L CaCO₃)	Sodium (mg/L)	Label Location	Availability	Notes
Nongfu Spring (农夫山泉)	100–150	40–60	Back label, "矿物质成分" (mineral composition)	Ubiquitous (supermarkets, convenience stores, gas stations)	Soft to moderately hard; suitable for all medication profiles. Most popular brand nationally.
Evian (依云)	60–80	6–8	Side panel, "营养成分信息" (nutritional information)	Department stores, upscale hotels, some supermarkets	Very soft European import; optimal for tetracyclines/bisphosphonates. Premium pricing (¥8–12 per 0.5L).
Wahaha (娃哈哈)	120–180	35–50	Back label under mineral content	Widespread (supermarkets, convenience stores)	Moderately hard; acceptable for most travelers. Budget-friendly (¥1.5–3 per 0.5L).
Cestbon (景田百岁山)	150–200	50–70	Back label, "产品成分"	Southern China, some national supermarkets	Moderately hard; avoid if taking bisphosphonates.
Just Water (怡宝)	80–110	20–30	Back label	Nationwide availability	Soft; excellent for medication-sensitive travelers.
Qingdao Beer (青岛啤酒) Purified Water (纯净水)	0–5	<5	Front label, "纯净水" designation	Large supermarkets, premium hotels	Distilled equivalent; safest for all medication classes.
Watsons (屈臣氏蒸馏水)	0–2	<2	Front label, "蒸馏水"	Watsons stores, department stores	Pure distilled water; ideal for tetracyclines, bisphosphonates, iron.

How to Read Chinese Labels

Key terms to locate:

• 矿物质含量 (Mineral content) – shows Ca, Mg, Na in mg/L
• 硬度 (Hardness) – displays °dH or mg/L CaCO₃
• 总溶解固体 (TDS) (Total dissolved solids) – indicator of overall mineral load
• 钙 (Calcium)
• 镁 (Magnesium)
• 钠 (Sodium)
• 纯净水 (Purified water) – indicates distilled/deionized

Pharmacist's Recommendations by Traveler Profile

General travelers (no medication concerns): Nongfu Spring, Wahaha, or Just Water. Affordable (¥2–5 per 0.5L), widely available, and moderately soft.

Travelers taking tetracyclines, bisphosphonates, or fluoroquinolones: Watsons distilled water or Evian. Prioritize distilled water (纯净水) labels. Cost is higher but ensures zero chelation risk.

Hypertensive travelers: Just Water or Evian (lowest sodium). Check the back label for sodium content; avoid brands exceeding 100 mg/L.

Travelers with infant formula: Watsons distilled water exclusively (see Infants section below).

Availability by City and Store Type

• Beijing, Shanghai, Guangzhou: All brands available in supermarkets (Carrefour, Auchan, Metro), convenience stores (7-Eleven, FamilyMart, Lawson), and pharmacies (China Pharmacy). Distilled water (Watsons, Qingdao) in major chains.
• Tier 2 Cities (Chengdu, Wuhan, Xi'an): Nongfu Spring, Wahaha, Just Water in local supermarkets; Evian/Watsons in premium hotels and department stores.
• Rural/Remote Areas: Nongfu Spring and Wahaha most common; distilled water may require hotel request or purchase from pharmacies (药店, yàodiàn).
• Pharmacies: Watsons distilled water, pharmaceutical-grade purified water (药用纯水), and some mineral brands; staff can advise on hardness if label is unclear.

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Ice, Tooth-Brushing, and Infant Formula Water

Ice (冰, bīng)

Risk Assessment: Ice in restaurants, bars, and street vendors is typically made from tap water and poses the same microbiological and mineral-load risks as tap water itself.

Specific Concerns:

• Bacterial contamination (Vibrio, Salmonella, Norovirus in poorly maintained ice machines)
• Parasite risk in southern regions (Giardia, Cryptosporidium)
• Freezing does not eliminate bacteria or viruses; it only preserves them

Pharmacist's Guidance:

• Avoid ice in street food, casual restaurants, and bars. Request drinks without ice or accept ice only in 5-star hotels with documented water treatment.
• If taking antibiotics: Ice-contaminated beverages could harbor Campylobacter or Salmonella, causing diarrhea that impairs your antibiotic absorption—a harmful cycle.
• Bring reusable ice gel packs if you need cold beverages; fill with bottled water and freeze in your hotel room.

Tooth-Brushing (刷牙, shuā yá)

Risk Assessment: Tap water for tooth-brushing poses minimal systemic risk (small volume swallowed) but contributes to cumulative mineral exposure in hard-water regions.

Specific Concerns:

• Fluoride levels in tap water vary; northern China's high-fluoride wells may cause dental fluorosis in children
• Hard water deposits may accumulate on teeth, causing discoloration and plaque buildup
• Swallowing tooth-brushing water during rinsing introduces bacteria and minerals

Pharmacist's Guidance:

• Travelers taking fluoroquinolones: Use bottled water to brush teeth, as fluoroquinolones' absorption is sensitive to mineral content in saliva and residual oral fluids.
• General travelers: Bottled water is safer for tooth-brushing; use sparingly to minimize swallowing. Alternatively, use tap water but limit to gentle rinsing.
• Children under 5: Use bottled or distilled water exclusively for tooth-brushing to minimize fluoride and bacterial exposure.
• Tip: Request bottled water (瓶装水) from hotel reception and keep a bottle in your bathroom.

Infant Formula Water (婴儿配方奶水, yīng'ér pèifāng nǎishuǐ)

Critical Importance: Infant formula requires distilled or sterilized water due to infants' immature immune systems and kidneys' inability to concentrate urine against high mineral loads.

Risks of Tap or Hard Water:

• Nitrate toxicity: Tap water can contain >45 mg/L nitrate (safe for adults, dangerous for infants <3 months; causes methemoglobinemia)
• Mineral overload: Infant kidneys cannot excrete excess calcium, magnesium, or sodium; accumulation leads to hypernatremia (elevated blood sodium), dehydration, and neurological damage
• Bacterial contamination: Infants lack gut flora to resist pathogens; diarrhea from contaminated water causes severe dehydration and electrolyte loss
• Fluoride excess: High-fluoride tap water combined with formula's inherent fluoride causes dental fluorosis

Mandatory Guidance for Travelers with Infants:

1. Purchase distilled water (蒸馏水) exclusively:

   • Watsons distilled water (widely available, ¥3–6 per 0.5L)
   • Pharmacy-grade purified water (药用纯净水) from pharmacies
   • Request "蒸馏水" (zhēngliú shuǐ) or "纯净水" (chúnjìng shuǐ) explicitly; do not accept "矿泉水" (mineral water)

2. Boil distilled water:

   • Boil for 1 minute (standard pot) or 3 minutes (high altitude >2000 m)
   • Cool to <45°C before formula preparation (kills pathogens; preserves nutrients)
   • Store in sterile bottles in refrigerator for up to 24 hours

3. Pre-boiled bottled water:

   • Some hotels provide "boiled water" (开水, kāishuǐ) in vacuum flasks; acceptable if bottle is clearly labeled and sterilized
   • Request confirmation from hotel management (in writing if possible)

4. Do NOT use:

   • Tap water (even "safe" tap water)
   • Mineral water of any kind
   • Filtered tap water (filters do not remove all pathogens or minerals)
   • Reheated or room-temperature boiled water (re-contamination risk)

5. Bring backup:

   • Pack 2–3 liters of pre-boiled, sterilized water in sealed bottles if traveling to remote areas or staying >5 days
   • Carry portable water sterilization tablets (chlorine dioxide, e.g., Aqua Mira) as emergency backup; follow infant-safe dosing

Pharmacist's note: Infants' formula reconstitution is non-negotiable. Even a single bottle made with tap water poses significant risk of gastroenteritis, which can be life-threatening in infants <6 months old. If you cannot secure distilled water, ask your hotel to provide boiled, sterilized water in advance or change hotels to one with documented water treatment.

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Considerations for Infants, Pregnant Travelers, and Renal Patients

Infants and Young Children (birth–5 years)

Water-Specific Risks:

• Nitrate toxicity: Infants <3 months cannot convert nitrite to nitrate; methemoglobinemia develops, causing "blue baby syndrome" (cyanosis, lethargy, seizures)
• Dehydration: Diarrhea from contaminated water causes rapid fluid loss; immature kidney-concentrating ability worsens dehydration
• Mineral overload: High sodium/calcium in hard water stresses developing kidneys
• Parasite risk: Giardia and Cryptosporidium cause persistent diarrhea in children; malabsorption delays development

Pharmacist's Guidance:

• Formula: Distilled water only (see Infant Formula section above)
• Drinking water (>6 months): Introduce small amounts (30–60 mL/day) of distilled water only; no tap water
• Teething water: Use distilled water for teething toys; do not offer tap water or ice
• Medications: If infant requires antibiotics (e.g., amoxicillin for ear infection), prepare with distilled water; hard water may reduce absorption (though aminopenicillins are less sensitive than tetracyclines)
• Preventive measures:
  • Breastfeeding infants need no water until 6 months; breast milk provides adequate hydration
  • After 6 months, introduce water gradually (distilled only)
  • Boil formula water and cool before feeding
  • Wash fruits and vegetables with distilled water before offering

Storage and Hygiene:

• Keep distilled water in sealed, sterilized bottles
• Label each bottle with date/time of boiling; use within 24 hours
• Do not reuse bottles; sterilize after each use (hot water wash + drying)

Pregnant Travelers

Water-Specific Risks:

• Iron absorption: Hard water reduces bioavailability of iron supplements (critical in pregnancy for preventing anemia and preterm birth)
• Calcium metabolism: Excessive hard water consumption may cause hypercalcemia, increasing preeclampsia risk
• Infection risk: Traveler's diarrhea triggers dehydration and electrolyte loss; in pregnancy, this stresses the fetus and may trigger preterm contractions
• Medication interactions: Prenatal vitamins (iron, calcium, magnesium) are chelated by hard water

Pharmacist's Guidance:

• Prenatal vitamin timing: Take with distilled water, 2 hours before consuming hard water or mineral water
• Iron supplementation: Essential for pregnancy-related anemia; take with vitamin C (orange juice) and distilled water, away from coffee/tea and hard water (separate by 2+ hours)
• Calcium supplementation: If prescribed for bone health or preeclampsia prevention, use distilled water and separate by 2+ hours from iron and other minerals
• Hydration: Pregnant women need 8–10 glasses of water daily; use bottled/distilled water exclusively to prevent infection and electrolyte imbalance
• Avoid diarrhea: Select distilled or soft water (Evian, Watsons, Just Water) to minimize infection risk; diarrhea-induced dehydration is especially dangerous in third trimester
• Sodium intake: Pregnant women should limit sodium to <2300 mg/day; monitor mineral water sodium content (target <100 mg/L); avoid high-sodium brands (Cestbon, Nongfu Spring in hard-water regions)

Nausea and hydration:

• Ginger-flavored water or water at room temperature (not cold, which may trigger nausea) aids tolerability
• Electrolyte drinks (oral rehydration salts prepared with distilled water) help if experiencing morning sickness
• Avoid caffeine in tea/coffee used with hard water; caffeine impairs iron absorption further

Renal Patients (Chronic Kidney Disease, Dialysis, Transplant)

Water-Specific Risks:

• Phosphate load: Hard water's high phosphate content (from minerals and some brands' additives) worsens hyperphosphatemia; controls bone metabolism and prevents secondary hyperparathyroidism
• Sodium retention: Mineral water with >150 mg/L sodium exacerbates hypertension and fluid overload; dialysis patients cannot excrete excess sodium
• Magnesium and calcium overload: Impaired renal clearance causes accumulation; excessive intake triggers hypermagnesemia and hypercalcemia
• Medication interactions: Renal patients often take phosphate binders (calcium acetate, sevelamer) with meals; hard water interferes with binder effectiveness
• Infection risk: Immunosuppressed transplant patients face severe consequences from traveler's diarrhea; dehydration worsens graft function

Pharmacist's Guidance—Dialysis Patients:

• Water intake:
  • Strict fluid restriction (typically 500–1000 mL/day plus urine output); hard water's minerals count toward total fluid intake
  • Monitor weight gain between dialysis sessions; hard water (denser than pure water) may cause unexpected gains
  • Use distilled water exclusively; it contains no added minerals to tax kidney function
• Medication timing: Take phosphate binders (calcium acetate, sevelamer) exactly as prescribed with meals prepared with distilled water; hard water reduces binder efficacy
• Potassium: If hyperkalemic, avoid mineral water high in potassium (rare in China, but check labels); use distilled water
• Sodium: Limit mineral water sodium to <50 mg/L; request hotel staff to provide distilled water (蒸馏水) or pharmacy-grade purified water (药用纯净水)

Pharmacist's Guidance—Renal Transplant Patients:

• Immunosuppression: Tacrolimus, cyclosporine absorption is moderately sensitive to mineral content; take with distilled water to maximize bioavailability
• Infection prevention: Traveler's diarrhea from contaminated water is especially dangerous; strict adherence to distilled/boiled water prevents graft-threatening infections
• Hypertension management: Transplant patients commonly develop hypertension; hard water's sodium and minerals elevate blood pressure; use low-sodium distilled water
• Drug interactions: Antirejection drugs interact with high-dose magnesium; use distilled water to minimize mineral load

CKD Stage 3b–5 (GFR <45 mL/min):

• Phosphate control: Mineral water high in phosphate (check label for "phosphate" or "磷") should be avoided; distilled water contains zero phosphate
• Bone health: Avoid excessive calcium and magnesium; parathyroid hormone (PTH) becomes dysregulated; hard water minerals worsen this
• Fluid balance: Hard water's dissolved minerals increase osmotic load; kidney may struggle to concentrate urine, worsening fluid retention
• Recommendation: Consult nephrologist before travel; carry distilled water from home if traveling to regions where it's unavailable (rural China)

All Renal Patients—Practical Tips:

1. Request hotel kitchen staff to provide distilled water in vacuum flasks (request in advance)
2. Carry portable water tests (hardness kit) to verify water mineral content if unsure
3. Prioritize Watsons distilled water (蒸馏水) or pharmacy-grade purified water (药用纯净水) from Watsons stores or pharmacies
4. Keep a written list of allowable water brands (distilled, <50 mg/L sodium) in Mandarin to show hotel staff
5. Request electrolyte panel before travel; know your potassium, phosphate, and sodium target ranges

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Summary

• Tap water in China is generally unsafe for travelers despite meeting national standards; use bottled, distilled, or boiled-and-cooled water exclusively. Urban tap water (Beijing, Shanghai) is microbiologically acceptable for locals but poses risk to visitors due to unfamiliar bacterial strains.

• Hard water is widespread, particularly in Northern China (Beijing 250–400 mg/L CaCO₃; Shanghai 150–250 mg/L). This hardness directly reduces absorption of tetracyclines, bisphosphonates, fluoroquinolones, and iron supplements by 20–90%.

• Medications requiring water caution:

  • Tetracyclines (doxycycline): Chelated by calcium/magnesium; take with distilled water, 2 hours before hard water
  • Bisphosphonates (alendronate): 90% absorption loss in hard water; use distilled water exclusively
  • Fluoroquinolones (ciprofloxacin): 20–50% reduction; separate from hard water by 2–4 hours
  • Iron supplements: Take with vitamin C and distilled water; avoid hard water (2+ hours apart)
  • Prenatal vitamins: Separate iron/calcium from hard water by 2+ hours

• Recommended mineral water brands:

  • General travelers: Nongfu Spring, Wahaha, Just Water (¥2–5/bottle, moderately soft)
  • Medication-sensitive (tetracyclines, bisphosphonates, iron): Watsons distilled water, Evian (distilled/very soft)
  • Hypertensive travelers: Just Water, Evian (<50 mg/L sodium)
  • Infants, pregnant women, renal patients: Watsons distilled water (蒸馏水) exclusively

• Check labels for mineral content: Locate "矿物质含量" (minerals) or "硬度" (hardness) on the back label; values in mg/L or °dH. Distilled water is marked "纯净水" or "蒸馏水."

• Ice is unsafe. Made from tap water, it preserves bacteria and viruses; avoid in restaurants/bars except 5-star hotels. Use ice gel packs filled with bottled water instead.

• Tooth-brushing with bottled water is safer, especially for fluoroquinolone users and children. Request bottled water from hotel reception.

• Infant formula requires distilled water boiled for 1 minute, cooled, and used within 24 hours. Tap or mineral water causes nitrate toxicity, dehydration, and electrolyte imbalance in infants <3 months. Non-negotiable safety measure.

• Pregnant travelers need distilled water for prenatal vitamins and hydration to ensure iron/calcium absorption and prevent infection-triggered preterm contractions. Limit mineral water sodium to <100 mg/L.

• Renal patients (dialysis, transplant, CKD Stage 3b+) must use distilled water exclusively to avoid phosphate, sodium, calcium, and magnesium overload. Hard water mineral density increases between-dialysis weight gain unexpectedly. Consult nephrologist before travel.

• Distilled water is universally safe for all travelers, medications, infants, pregnant women, and renal patients. Watsons distilled water is widely available in major cities (¥3–6/bottle) and pharmacies; request "蒸馏水" explicitly.

• If diarrhea develops, suspect contaminated water; oral rehydration salts (prepared with distilled water) and medication absorption may be impaired for 12–24 hours. Seek medical care if symptoms persist >3 days.

• Travel insurance should cover medical consultation for medication efficacy concerns or water-related illness. Keep receipts for distilled water purchases; some insurers reimburse preventive supplies.