• Recommended Procedure for Disinfection of Small Quantities of Drinking Water
• Recommended Procedure for Chlorine Disinfection of Water Wells
• Recommended Procedure for Chlorine Disinfection of Spring Box, Ground Reservoir...

Recommended Procedure for Disinfection
of Small Quantities of Drinking Water

Boiling is a very effective means of disinfection drinking water, but the process is bothersome and not often used. Chemical disinfection of small quantities of water for human consumption is much more popular, and if carefully accomplished is as effective as boiling.

Four items must be considered if chemical disinfection is to be effective: (1) the water must be free of turbidity or dirt, (2) the chemical must be applied in a sufficient amount to guarantee disinfection and must be uniformly distributed to contact every particle of water, (3) at least 30 minutes of contact time must be provided between the chemical and water to allow time for the chemical to destroy any disease causing bacteria or viruses, and (4) the water after treatment must be protected from further contamination.

The most widely used chemical for water disinfection is chlorine. This chemical is used by most municipal water systems and effectively destroys disease causing bacteria and viruses when applied in dosages far below the amount harmful to humans. The chemical can be purchased in the form of chorine gas, chlorine powder, or liquid chlorine. Household bleaches such as Clorox and Hilex are liquid chlorine. This form is best for treatment of small quantities of water because no equipment is required and the liquid can be easily measured by a dropper, spoon, or measuring cup.

Typically household bleaches will be 5.25% available chlorine., although it is possible to have slightly different solution strengths depending on the particular product. The first step in disinfecting drinking water is to determine the % available chlorine in the solution that can be obtained from grocery stores.

The next step is to determine the amount of chlorine to use in properly treating a quantity of water. The following table gives the amount of chlorine necessary to treat given quantities of water. By knowing the amount of water to be treated, the amount of solution can be determined from the table.

The water to be treated should be place in a clean container. After the chlorine solution is introduced into the water, it should be agitated slightly to mix the chlorine and water. The container should then be covered and the water allowed to stand for at least 30 minutes before using. An odor and taste of chlorine should be apparent. These will disappear with time, are entirely harmless to humans, and are your guarantee of safe drinking water.

Recommended Procedure for Chlorine Disinfection of Water Wells
(Reference - AWWA A100-6, Standard for Deep Wells)

Introduction

A water well should be thoroughly cleaned and disinfected with a strong chlorine solution after:

Adequate chlorine requires a certain chlorine dosage for a minimum contact time - 100 parts per million for 2 hours, or 50 parts per million for 8 hours, or 25 parts per million for 24 hours.

Chlorine for disinfection for these water systems can be either 5.25% sodium hypochlorite solution or 65% calcium hypochlorite powder. A 5.25% hypochlorite solution is common house-hold bleach such "Hilex", "Clorox", or "Purex" available at grocery stores and supermarkets. The 65% calcium hypochlorite powder is available from chemical supply houses and is known commercially as "HTH", Perchloron", or "Pittchlor".

Recommended Procedures

1. Determine the chorine dosage for the desired contact time from the following table:

2. Prepare a chlorine solution, lift well pump, and pour the chlorine solution into the well.
3. Lower the pump and operate until a chlorine odor is noticed at all discharge points.
4. Leave the chorine solution in the unit for the recommended contact time. Do not use the water.
5. At the end of the contact time, pump the well to waste until the chlorine odor cannot be detected.
DO NOT ALLOW THE WATER TO ENTER A RIVER, LAKE, OR STREAM.
6. Pump the well for considerable period of time and collect a bacteriological water sample and submit it for testing.

Recommended Procedure for Chlorine Disinfection of Spring Box,
Elevated Storage, Ground Reservoir, Cistern, Water Treatment Plant Basin

Introduction

A ground reservoir, elevated tank, spring box, cistern, or water treatment plant basin should be thoroughly cleaned and then disinfected with a strong chlorine solution after:

Adequate chlorine requires a certain chlorine dosage for a minimum contact time - 100 parts per million for 2 hours, or 50 parts per million for 8 hours, or 25 parts per million for 24 hours.

Chlorine for disinfection for these water systems can be either 5.25% sodium hypochlorite solution or 65% calcium hypochlorite powder. A 5.25% hypochlorite solution is common house-hold bleach such "Hilex", "Clorox", or "Purex" available at grocery stores and supermarkets. The 65% calcium hypochlorite powder is available from chemical supply houses and is known commercially as "HTH", Perchloron", or "Pittchlor".

Recommended Procedures

1. The unit to be disinfected should be full of water.
2. Determine recommended chlorine disinfection dosage for the desired contact time from the following table:

3. Completely mix the chorine dosage throughout the unit to be disinfected.
4. Leave the chorine solution in the unit for the recommended contact time.
5. Do not use the heavily chlorinated water.
6. At the end of the contact time, remove the water from the unit and discharge to waste.
DO NOT ALLOW THE WATER TO ENTER A RIVER, LAKE, OR STREAM.
7. Fill the unit with clean water and collect a water sample for bacteriological testing after one or two days of use.