Our office does not recommend residents or visitors drink, consume or cook ground water with nitrate concentrations which exceed the Maximum Contaminant Level (MCL) of 10 milligrams per liter (mg/L) of nitrate. This MCL is based upon research carried out by the Environmental Protection Agency (US EPA).
Infants below the age of six months who drink water containing nitrate and/or nitrite in excess of the MCL could become seriously ill and, if untreated, may die. Symptoms include shortness of breath and blue baby syndrome. These risks also affect nursing mothers and unborn infants. To address this issue, our office recommends the well owner and other users of the contaminated water well establish a contingency plan that includes, at minimum, the following items:
- A procedure to collect a confirmation water sample for nitrate within 24 hours of receiving the analytical results, of the original sample, from the laboratory.
- Preparation of a Do Not Drink Notice to all parcels serviced by the contaminated water well.
- Corrective action plan: In the event that the nitrate level continues to exceed the MCL, a corrective action plan will aid the well owner in outlining their approach. The plan should address the following:
- Acquisition of another suitable supply of water;
- Treatment of the source water under the supervision of a Clark County contractor or plumber familiar with Chapter 6 of the Uniform Plumbing Code and National Sanitation Foundation private domestic treatment plant standards;
- Consolidation with an adjacent public water system that provides water of sufficient quantity and quality; or
- Any other actions sufficient to return bring nitrate concentrations below 10 mg/L.
Recommendation 3b may be addressed using either reverse osmosis, electrodialysis/ED Reversal, or anion exchange treatment. These treatment methods are recognized by the American Water Works Association as generally effective treatment processes for nitrate. In rare cases, depending upon initial nitrate concentrations, more than one treatment unit may be needed in series to achieve a reliable and consistent below 10 mg/L nitrate concentration. It is ultimately the responsibility of the well owner and each individual parcel owner to:
- pilot these treatment options and determine if nitrate will be effectively treated below 10 mg/L, and
- to maintain treatment media for the duration of time the contaminated water well source is used to provide water for drinking and culinary purposes.
Our office understands these treatment options are expensive. In most cases, it is only necessary to treat water that is destined for consumption and culinary purposes. Therefore, a cost-effective method of treatment would be to install a point-of-use nitrate treatment unit within the parcel owner’s home, and all other homes which draw water from the referenced water well.