Hesperian Health Guides

Water and Health

 woman carrying an infant, a bag, and a water jug

Water is essential for life. We need it, as do the animals and plants that we depend on for our survival. In communities that lack adequate water, many health problems arise.

  • Without water, people cannot grow enough food to eat, leading to malnutrition and the many health problems that go along with it.
  • Infections of the eyes and skin arise when people cannot use water to bathe. Other illness also spreads more quickly when people cannot stay clean.
  • Those who collect the water (usually women and children) spend much of their time in the exhausting work of traveling to and carrying water. This leaves little time for school, other work at home, or community life.

Water that is safe to drink

In addition to enough water, people also need water that is safe to drink, free of dangerous germs and harmful chemicals. Contaminated water causes:

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  • hepatitis A, typhoid fever, and other
    deadly diseases.
  • diarrhea, which leads to dehydration and
    can cause death especially for children.
  • infections such as schistosomiasis that can lead to anemia
    and malnutrition.

Different methods for making water safe are described below. It is also important for your community to prevent water from being polluted or made scarce in the first place.

With enough safe water, children grow healthier and have less diarrhea disease.

Collecting water

Water should be taken from the cleanest possible place. When collecting water from rivers,
collect upriver from:

 stream beside farm and village, with defecating cow, trash, and person washing clothes in it
farms that use chemical pesticides or fertilizers
where people or animals defecate
where people bathe, or wash dishes or clothes
any pollution from homes (trash, gas, or oils)

Collecting rainwater

 pieces of bamboo hanging off roof to collect rain water

Rainwater is easy to collect off roofs and into containers placed next to the house. Roofs made of tin or corrugated metal are best to catch water. The water needs to be treated (see below) to make it safe to drink because there may be germs on the roof from dirt, or feces from birds or other animals. However, do not use water collected from roofs made with lead, asbestos, or tar because these have toxic chemicals in them that make water collected on them unsafe to drink. When collecting or storing rainwater, make sure your container is clean and was never used to store chemicals, such as oil or pesticides.

Making water safe to drink

Making water safe to drink is one of the best ways to prevent diarrhea and disease. Water from any source will need to be treated if there are germs in it. Even if water from pipes, tanks, or wells looks clear, it could still be contaminated and needs treatment.

When deciding which water treatment method to use, think about how much water you need, what it is contaminated with, and what resources are available. The chart below can help you decide which method to use if you know a particular problem is common in your area. The method you use may change depending on the season or where you are. For example, you may use one method at home and another when you are working in the fields.

Problem Filter methods Disinfection methods
Cloth Filter Charcoal Filter Boiling Chlorine Sunlight Lemon or Lime juice
Viruses (such as hepatitis A and typhoid)
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Bacteria (such as shigella and e. coli)
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This chart shows which germs and parasites the different methods kill. The water drop in the chart means that method is effective at killing that germ.

If there is more than one cause of water-borne disease where you live (which is often the case), the best solution may be to combine two methods: filter and disinfection.

Filtering water

There are many ways to filter water to make it safer. Cloth and charcoal filters are explained below. Other kinds of filters, such as slow sand and ceramic filters, are explained in A Community Guide to Environmental Health

If your water is not clear, first let the water settle in a container for a few hours to allow dirt, solids, and parasites to fall to the bottom of the container. Pour the clear water through the filter. Try not to disturb the dirt that settled to the bottom of the container. Then clean the container.

Cloth filters

In Bangladesh and India, people use a filter made of finely woven cloth to remove cholera germs from drinking water. The cholera germ often attaches to a tiny animal that lives in water, and filtering out these animals also filters out most cholera germs. You can make a cloth filter out of handkerchiefs, linen, or other fabric such as the cloth used to make saris. Old cloth works better because worn fibers make the spaces in the weave smaller and better for filtering.

two women filter water by pouring it through a cloth into a jar
  1. Let water settle in a container so that solids sink to the bottom.
  2. Fold the cloth 4 times and stretch or tie it over the mouth of another container or jar.
  3. Pour water slowly from the first container through the cloth into the second container or jar. Always use the same side of the cloth, or germs may get into the water.
  4. After using the cloth, wash it and leave it in the sun to dry. This kills any germs that may be left in the cloth. In the rainy season, disinfect the cloth with bleach.

Charcoal filters

To make a charcoal filter, you will need 2 clean metal or plastic buckets, a hammer, 1 or 2 large nails, a bucketful of coarse sand, and ¼ bucket of wood charcoal.

  1. Make holes in the bottom of one of the buckets. Wash the bucket. This will be the filter bucket.
  2. Clean the sand by rinsing it in water and draining until the water that drains is clear.
  3. Put a layer of washed sand 5 cm deep into the filter bucket and pour water over it. Water should run out through the holes. If no water runs out, make the holes bigger. If sand runs out, the holes are too large. If this happens, remove the sand, place a thin cloth over the holes, and replace the sand.
  4. Crush charcoal into small pieces. Activated charcoal works best, but ordinary wood charcoal will also work. Never use charcoal briquettes, they are poison!
  5. Place a layer of crushed charcoal about 8 cm deep on top of the sand. Then fill the bucket with more washed sand until the sand is 10 cm below the top of the bucket.
  6. Place 2 sticks on top of the second bucket and set the filter bucket on these sticks. Pour clean water through the filter bucket. When the water comes out clear into the collecting bucket, the filter is ready for use.
     pouring water through charcoal filter
    Filter bucket
    Open 10 cm
    8 cm charcoal
    5 cm sand
    Sticks to hold bucket
    Clean collecting bucket
  7. Allow water to settle before pouring it through the filter.

Because the germs that are filtered out will grow on the charcoal, it is important to remove and clean the charcoal every few weeks if the filter is used daily, or any time the filter has been unused for a few days. To clean the charcoal, take it out of the filter and run water over it until it drains quickly. Let it dry, in bright sun if possible. Then put the charcoal back in the filter.

It is even safer to disinfect water after filtering by boiling, adding chlorine, or using sunlight.

Disinfect Water

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Boiling water for 1 minute kills germs and makes water safe for drinking.

Boiling water

Bring water to a rapid boil. Continue boiling for 1 full minute before taking the pot off the fire to cool. In high mountain areas, water must boil for 3 minutes.

Boiling may change the taste of water, especially if boiled over a wood fire. If the taste bothers you, pour the cooled water in a bottle and shake it. Shaking adds air to the water and improves the taste.

Boiling water after food is prepared, but before the fire dies, is one way to use less firewood.


The amount of chlorine needed to disinfect water depends on how contaminated the water is. The more germs there are in the water, the more chlorine is needed to kill them. When the correct amount is used, the water will smell and taste just slightly of chlorine. This tells you it is safe to drink. If it has too much, the smell and taste will be strong and unpleasant.

Chlorine comes in different concentrations. The amounts listed below show how to disinfect water using household bleach with 5% chlorine (sodium hypochlorite). Read the label to see what percent of chlorine is in your bleach. If the bleach is 3% chlorine, you will need to use more. If your bleach label includes instructions for disinfecting water, follow those instructions. Do not use bleach that has soap or perfume added to it.

If the water is cloudy or has a lot of solid matter in it, filter the water before adding chlorine.

Water Add Bleach (5%)
For 1 liter or 1 quart
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For 1 gallon or 4 liters
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For 5 gallons or 20 liters
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For a 200 liter barrel
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After adding the right amount of chlorine, stir well and wait at least 30 minutes before drinking. If the water does not smell or taste just slightly of chlorine after adding the amount listed, add the same amount again. Stir and wait before drinking.

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Sunlight (solar disinfection) works best in countries close to the equator, because the sun is strongest there. The farther north or south you are, the more time is needed for sunlight to work.

Filtering the water first to make it clearer will also make it disinfect more quickly. Clean a plastic or glass bottle, or a plastic bag. Clear plastic soda bottles are the best to use. Fill the bottle half full, then shake it for 20 seconds. This adds air bubbles which help disinfect the water faster. Then fill the bottle to the top. Place the bottle where there is no shade and where people and animals will not disturb it, such as the roof of a house. Leave the bottle for at least 6 hours in full sun, or for 2 days if the weather is cloudy.

 two juicy lemon halves and a liter bottle
Use 1 lime or lemon for every liter of water

Lemon or lime juice

Add the juice of a lemon or lime to 1 liter of drinking water and let it sit for 30 minutes. The acid from the juice will kill most cholera and some other germs as well. This method is not very good because plenty of germs may remain in the water, but it is better than no treatment, especially in areas where there is cholera.

Store water safely

After water has been filtered or disinfected it must be stored safely. Otherwise it can easily become contaminated again. Water stored in tanks with cracked walls may not be safe. Likewise containers with loose, poorly made, or missing covers, do not prevent water from becoming contaminated by germs.

Covered tanks and cisterns are safer for storing water than open tanks because mosquitoes and snails cannot live in closed containers. Locate water storage as close as possible to where the water will be used.

Stored water can also become unsafe when it is touched by dirty cups, dirty hands, when clean water is poured into a dirty container, or when dirt or dust gets in the water.

To prevent water from becoming contaminated during storage:

a water container with a long-handled dipper
  • pour water out without touching the mouth of the container, or use a clean, long-handled dipper to take water out of the container. Do not let the dipper touch anything else, or it will contaminate the clean water when it is used again.
  • empty and clean out the container with hot water every 2 or 3 weeks.
  • keep containers covered.
  • keep drinking cups clean.
  • never store water in containers that have been used for pesticides or toxic chemicals.
  • do not treat more water than you need for short-term use, if possible. For drinking and preparing food, that is usually about 5 liters for each person each day.
NWTND was Page 25-2.png Narrow mouthed containers keep more germs out, so are safest for storing water.

Water for everyone

Good health depends on having enough good water. This means our right to health depends on our right to water. While we can work to protect water sources, and treat water to make it safe, our health is still threatened if mining, run-off from fertilizers and pesticides, or factories pollute our water.

Governments and communities must work together to protect, improve, and extend water systems so they provide people with enough safe water. Private companies say if we let them take control of our water, they can provide better service than governments and still make a profit. This is called water privatization. But usually what happens is that the price of water goes up, denying people access to their own water. This leads to serious health problems when people use less water than they need or when they collect water wherever they can for free, even if the water is contaminated with germs or toxic chemicals.

To keep people and the environment healthy, we need public water systems that provide water that is safe to drink for everyone. Community controlled water systems can be managed so people’s health, not making money, is the top priority.

This page was updated:11 Feb 2019