Well Water—What Happens 
When Tests Find a Problem

Sara Thompson, KP News

Editor’s note: Following the January KP News article on wells and water systems, some readers asked about the consequences of testing their wells and finding a problem. KP News pursued the matter with Brad Harp, program manager for water resources and hazardous waste at the Tacoma-Pierce County Health Department.

There are three classes of water systems on the Key Peninsula, each with different testing requirements, Harp said. Group A systems (for 15 or more homes) must be managed by a certified operator, with testing requirements depending on the size of the system and previous test results, all of which are monitored by the Washington State Department of Health.

The Tacoma-Pierce County Health Department follows Group B systems (with two to 14 homes), with testing for coliform bacteria required annually and for nitrates every three years. Although no testing is required for existing private wells, the health department encourages owners to test their wells on the same schedule as the Group B systems.

If routine testing shows either nitrate or coliforms, the health department will contact the Group B owner or manager. If the well is private, no action is required, though for safety reasons, the health department recommends the same corrective actions required of Group B systems.

The first step is to repeat the test, Harp said. Water is often sampled incorrectly—perhaps from a hose or a spout that was not cleaned adequately. If there is still a problem after repeat sampling, the health department will work via a phone call to identify possible sources of contamination that can be corrected. Are there rodents near the wellhead? Is fertilizer being used nearby? Is livestock within close range?

If no clear cause can be identified and corrected, then treating water with chlorine will combat coliforms. A special filter can remove nitrates. Once a test shows clear results, the frequency of testing returns to the usual recommended intervals.

According to the Washington State Department of Health website, the presence of coliforms (a type of bacteria) is an indicator for water quality. Coliforms are commonly found in soil and vegetation and most are harmless, but some are found in feces (fecal coliforms) and of those, some can cause serious gastrointestinal illness.

Nitrate is found in most fertilizers, manure and liquid waste discharged from septic tanks. Natural bacteria can also change nitrogen to nitrate. Rain or irrigation water can carry nitrate down through the soil into groundwater, and drinking water may contain nitrate if a well draws from this groundwater. Nitrate reduces the ability of red blood cells to carry oxygen and can cause blue baby syndrome in infants.

For further information, go to tpchd.org/healthy-homes.