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Nutrition and daily life

Well water and bottled water

In villages and country houses well and spring water are widely used. It can look clean but carry bacteria, parasites or nitrates. This section explains how to judge well, spring and bottled water.

Last updated: ~1 min read
A stone well in shadow.
Figure 1.A village well — Well water and bottled water

01Short answer

During treatment do not drink untested well or spring water, wash fruit and vegetables in it or make ice from it. Choose bottled water with an intact sealed cap; do not buy it if the seal is broken. Finish an opened bottle within 1 day, drinking from a glass rather than the bottle. If there is no other option, boil well water vigorously for at least 1 minute. Well water is especially risky after rain or flooding and near livestock farms. Clean water-cooler dispensers regularly.

02Simple explanation

No well or spring water.

A sealed bottle.

Opened: 1 day.

If needed, boil.

03Scientific explanation

WHO: unprotected wells and springs are open to faecal contamination and are a source of diarrhoea and other infections.

WHO: foodborne illness is more severe in people with weakened immunity; the five keys are keep clean, separate, cook thoroughly, keep food at safe temperatures, and use safe water and raw materials.

04What happens in the body?

Water testing

Well water can be lab-tested for microbes and chemicals.

A bottle with an intact cap.
Figure 2.A sealed bottle — Well water and bottled water

Water coolers

The tap and reservoir of a dispenser can harbour bacteria.

A roadside spring in shadow.
Figure 3.A spring — Well water and bottled water

Neutropenia

When neutrophils are low, even ordinary germs can cause serious infection, which is why the rules are stricter.

General rules

This section is part of the general food-safety rules in “Handwashing: the simplest protection” and “Eggs and dairy: safe choices” and “Food safety: four simple rules”.

05Safety: four steps

Check, swap the risky, prepare properly, use in time.

Check — Date and condition.1CheckDate and condition.
Swap — A safe choice.2SwapA safe choice.
Prepare — Clean and thorough.3PrepareClean and thorough.
In time — No delay.4In timeNo delay.
CleanHands and surfaces.
CookGerms die.
ColdGrowth slows.

06Key points at a glance

TopicIn brief
Water testingWell water can be lab-tested for microbes and chemicals.
Water coolersThe tap and reservoir of a dispenser can harbour bacteria.
NeutropeniaWhen neutrophils are low, even ordinary germs can cause serious infection, which is why the rules are stricter.
General rulesThis section is part of the general food-safety rules in “Handwashing: the simplest protection” and “Eggs and dairy: safe choices” and “Food safety: four simple rules”.

07Key terms

Nitrates
Chemicals from fertiliser that can enter water.
Seal
A ring showing a bottle has not been opened.
Foodborne infection
An infection spread through food or water.
Neutropenia
Low neutrophils.

08Key points

  • Avoid untested water.
  • A sealed bottle.
  • Boil if needed.
  • When in doubt, throw it out.
  • Call if you have a fever.

09Frequently asked questions

Is mineral water OK?

In a sealed bottle, usually yes.

People say spring water is very pure?

Looks are no guarantee of safety; avoid it during treatment.

Are these rules for ever?

No. They are usually relaxed as blood counts recover; your team will say.

10Questions for your doctor

Take these questions to your appointment. The ones you save are collected on the “My questions” page and stay on this device only.

  1. Is mineral water OK?

  2. People say spring water is very pure?

  3. Are these rules for ever?

My questions

12Sources

  1. World Health Organization. Drinking-water fact sheet
  2. World Health Organization. Five Keys to Safer Food manual
  3. World Health Organization. Food safety fact sheet
  4. U.S. Food and Drug Administration. Safe Food Handling
  5. National Cancer Institute. Eating Hints: Before, During, and After Cancer Treatment
  6. U.S. Food and Drug Administration (FDA). Dietary Supplements
  7. Clinical Pharmacology & Therapeutics, 2004. Effect of St John’s wort on imatinib mesylate pharmacokinetics
  8. Journal of Clinical Oncology, 2020. Dietary Supplement Use During Chemotherapy and Survival Outcomes of Patients With Breast Cancer Enrolled in a Cooperative Group Clinical Trial (SWOG S0221)
  9. Macmillan Cancer Support. Tiredness (fatigue) and cancer
  10. Journal of Clinical Oncology, 2024. Management of Fatigue in Adult Survivors of Cancer: ASCO–Society for Integrative Oncology Guideline Update
Medical disclaimerThis information is for educational purposes only and does not replace medical advice.
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