Design and Cost Considerations
Small Systems Treatment Technologies Research
- How EPA Determines whether Compliance with a Drinking Water Standard is Affordable
- Alternatives to Centralized Treatment
- Drinking Water State Revolving Fund
EPA identifies affordable small systems treatment technologies to meet drinking water standards.EPA evaluates technologies and their costs for three small systems categories:
- Systems serving 25 to 500 people
- Systems serving 501 to 3,300 people
- Systems serving 3,301 to 10,000 people
If affordable technologies cannot be found, EPA identifies variance treatment technologies. These variances must achieve the maximum reduction affordable and protect public health.
EPA compares the current cost of water plus the estimated additional treatment cost of a drinking water standard to an affordability threshold of about $1,000. This is calculated by taking 2.5 percent of the annual median household income of about $40,000 among small system customers. EPA has found compliance with all new drinking water regulations to be "affordable" using this ceiling. As a result, states have not granted small system variances.
However, there may be a significant number of systems that have struggled with compliance costs for some recent regulations. Small system operators state that the current criteria are too stringent. Also, the criteria fail to recognize situations where small systems find a regulation too expensive to meet.
The Science Advisory Board and National Drinking Water Advisory Council made these key recommendations:
- EPA should consider the household cost of each new regulation on an incremental basis rather than on the basis of a total cost of all water treatment regulations
- EPA should consider reducing the current affordability threshold. The options being considered by EPA are based on a range of income percentages significantly below the current threshold. This is more likely to make variances available to small drinking water systems.
EPA proposed that a variance technology for regulated contaminants be considered protective of public health if the concentration is no more than three times the MCL. This as a general guideline. This may be modified for a specific contaminant if:
- unusual factors are associated with the contaminant or
- a risk assessment suggests that an alternate level, whether higher or lower, is appropriate.
Note: SDWA does not allow small system variances for microbial contaminants.
Many small public water systems are unable to comply with the SDWA. Often state and local governments are forced to seek alternatives to centralized treatment.
In many cases, it may be more cost effective to install POU/POE units. This might be an appropriate solution for utilities that serve up to 100 homes, depending on the cost of the POU/POE.
Bottled water can be considered a principal alternative source. The use of bottled water has been recognized by the U. S. Army Corps of Engineers, the Federal Emergency Water Administration, and EPA under the National Contingency Plan for responding to contamination of drinking water supplies.
It can serve as a permanent supply of drinkable water for an entire small community or non-community system, or for residential areas. It is an attractive option when centralized treatment is too costly. In some scenarios, a central treatment station that delivers bottled water to each customer may be the best option. It eliminates the need for expensive treatment of water that is used for activities such as toilets, yard watering, and laundry. The SDWA allows EPA to authorize the use of bottled water, where appropriate.
Many public water systems face a lack of funding for infrastructure improvements that would enable them to comply with drinking water standards and protect public health. The SDWA allows EPA to provide funding to states, which in turn provide low-interest loans to drinking water systems for infrastructure improvements. The program also emphasizes providing funds to small and disadvantaged communities and to programs that encourage pollution prevention as a tool for ensuring safe drinking water. The program also emphasizes providing funds to small and disadvantaged communities.