Division of Environmental Health Food Safety and Sanitation Program

Potable Water Collection and Treatment Best Practices

Introduction

An adequate supply of safe drinking water is essential for any remote camp operation. If water is not properly treated, pathogenic microorganisms may cause serious illness. All water used for drinking water, cooking, and bathing should be treated to potable water standards.

For camps using surface water as the source of water, filtration and disinfection are required to remove or inactivate microorganisms, such as bacteria, viruses, and protozoa.

Camps using ground water as a source are not required to provide treatment. However, filtration may be used to remove particulates, such as sand, iron, and manganese that are common in ground water.

All treatment materials and chemicals used in potable water treatment must be approved for use in potable water by the National Sanitation Foundation (NSF), Underwriters Laboratory (UL), or equivalent organization that evaluates products using NSF Standards 60 and 61.

Potable Water Collection

Most remote camps will be using surface water as a source of drinking water. Before water can be treated, a source must be selected. Care should be taken in selecting a water collection point for the camp.

Typically, microorganisms are concentrated in stagnant or slow moving water, such as lake shores or along stream banks. These areas should be avoided if possible.

It is also important to avoid any body of water that has an algae bloom or has a strong organic odor because these conditions are associated with higher concentrations of microorganisms.

The best places to collect water are from a flowing portion of a stream or from a lake as far away from the shoreline as possible. When collecting water it is important to be careful not to stir up sediment because microorganisms tend to be concentrated in sediments. All materials used in transmitting water to the camp, such as hoses, must be approved by the NSF or an equivalent organization.

If a ground water well is going to be developed to supply drinking water to the camp, it is important to select the proper location for the well and to use the proper materials to develop the well. Ground water wells should be located at least 500 feet from any surface water source, 200 feet from any wastewater or graywater disposal area, and 100 feet from any above ground or below ground fuel storage tanks.

Ground water wells should be drilled to a sufficient depth, cased, and grouted to avoid influence by surface water. Currently, ground water is not required to be treated; however, filtration may be used to remove particulates, such as sand, iron and manganese. Disinfection may also be used to treat for microorganisms. All materials used in the development and treatment of well water for potable uses must be approved by the NSF or an equivalent organization.

Please see the Drinking Water regulations for more information.

• 18 AAC 80 Drinking Water
• 18 AAC 80.015 Well protection, source water protection, and well decommissioning
• 18 AAC 80.020 Minimum separation distances

Potable Water Treatment

The primary organisms of concern in drinking water are bacteria, viruses and protozoa. The state and federal drinking water regulations require that these organisms be adequately removed or inactivated from potable water. In order to achieve removal and inactivation, surface water can either be properly boiled or filtered and disinfected.

Boiling

Boiling is the simplest method of water treatment. Boiling water for two minutes is adequate to kill bacteria, viruses, and protozoa.

If water is relatively clear, it can be boiled without any pretreatment. If the water source has heavy amounts of sediment, it may be necessary to pre-treat the water before boiling.

Pretreatment can be done either with a coagulant or filtration. A coagulant is a chemical added to the water that attaches to any suspended solids present in the water and forms small clumps that will settle out. A common coagulant used for pretreatment is aluminum sulfate, or alum. The coagulant dosage is dependent on the sediment concentration, but usually is five to 90 milligrams per liter (mg/L), which is approximately two teaspoons of alum per five gallons of water.

After adding alum to the water, it must be allowed to settle for at least 30 minutes. After the suspended particles have settled, the clear water can then be poured into a clean container and boiled or disinfected. There are numerous other chemical coagulants available. Please check the manufacturer’s recommendations for usage and dosage.

Filters designed to remove sand and other sediments can also be used to pre-treat cloudy water. There are numerous filters on the market for this use. Selection of an appropriate sediment pre-filter would depend on the amount of water to be filtered and on the density and size of the sediment to be removed.

For small temporary camps, pre-treatment filtration would be a better option than coagulation for treating cloudy water prior to boiling.

When boiling is used for treatment, water should be brought to a rolling boil and allowed to boil for two minutes. If the camp is located at higher elevations, it will be necessary to boil water longer to achieve inactivation (Table 1). After boiling, it is important to store the water in a clean container to avoid contamination.

Table 1.

Water Treatment by Filtration and Disinfection

If surface water is being used as a source of drinking water, state and federal regulations require that the water be filtered and disinfected to remove or inactive pathogenic microorganisms. Two of the most common pathogens encountered in Alaska are Giardia and Cryptosporidium. These are pathogenic protozoa that cause disease in humans if they are ingested in drinking water. Both of these organisms are very resistant to chemical disinfectants, such as chlorine and iodine. Consequently, the most reliable method for removing Giardia and Cryptosporidium from drinking water is by filtration.

During filtration, raw water is passed through a porous material that separates contaminants from the water. Filters are typically constructed of fabric, special media, or ceramic. In order to achieve acceptable levels of removal of Giardia and Cryptosporidium, filters must meet the specifications of NSF Standard 53. If a filter meets this standard, it should be indicated on the label or in the manufacturer’s specifications.

Disinfection is done after filtration to inactivate any microorganisms, such as bacteria and viruses, which are too small to be removed by filtration. The two most common disinfectants used to treat drinking water at remote camps are chlorine and iodine.

Iodine is typically not very effective against enteric viruses or pathogenic bacteria, so chlorine is the most widely used disinfectant for water treatment. Liquid chlorine is available for drinking water uses at a concentration of about 5.25 percent available chlorine. Please note that liquid household bleach is not recommended for disinfecting drinking water because it may contain additives that reduce its effectiveness as a disinfectant.

The temperature and pH of the water being treated affect the effectiveness of the free available chlorine. In general, for chlorine to be effective, the pH of the water should be between 6.5 and 8.5. Table 2 shows the proper amount of liquid chlorine to use to disinfect small volumes of drinking water.

Table 2. Dosage for 5.25 percent to 6.00 percent Liquid Chlorine

Note: If a tablespoon is used for measuring, use one tablespoon for each three teaspoons.

Chlorine needs to be in contact with the water for a specified period of time to achieve adequate inactivation. This is called contact time.

Table 3 shows the amount of time (in minutes) needed to achieve 3-log inactivation of Giardia cysts at the typical water temperatures and pH levels found in Alaskan surface waters. It is advisable to have at least two containers at all times to ensure that the potable water is meeting adequate contact times.

Table 3.

Potable Water Storage

After treatment, it is important that drinking water be stored in sanitary containers to prevent contamination. All containers should be properly washed, sanitized with a chemical sanitizer approved by the Food and Drug Administration (FDA), and air dried before use.

Regulatory References

• 18 AAC 80 Drinking Water
• 18 AAC 80.015 Well protection, source water protection, and well decommissioning
• 18 AAC 80.020 Minimum separation distances

Resources and Contacts