Three sections of the Department of Environmental Services (DES) provide assistance to citizens with private well problems. These sections are the DES Laboratory Services Unit, the Water Supply Engineering Bureau and the New Hampshire Water Well Board. Their addresses and telephone numbers appear at the end of this document.

For the most part, this document assumes you are evaluating the installation of a new point well type water supply source for domestic home use. These wells are called "washed wells." In many cases there is relatively little choice in well type since this decision is so controlled by the type of soil and the height of the water table on your property. Suggestions concerning inspection of existing point wells can be found on page 5-6. For information concerning well abandonment see the DES fact sheet WD-WSEB-1-7.

There are statewide design criteria rules pertaining to point well construction and placement. These rules were originally adopted by the Board in 1983 and revised in 1997. The rules are numbered We 100-900. There are no state requirements concerning minimum waterquality orquantity for private home wells.

Finally, RSA 477:4-c requires, when selling a home with an on-site water system, disclosure of the water system's location, malfunctions, date of installation, date of the most recent water test and whether or not the seller has experienced a problem such as an unsatisfactory water test.

Local Regulations: Some towns may have local permit requirements relative to the placement, construction, water quantity or quality for private point wells. Please contact your local health officer or code enforcement officer for particulars.

DES has published a document entitled "Well Yield, How Much Water is Enough?" which is available for $2.00 through the Water Well Board. The United States Department of Agriculture, Farmers Home Administration Guidelines require a minimum well yield of 1200 gallons for a four-hour period (an average pumping rate of 5 gallons per minute).

Large non-pressurized storage tanks can serve to accumulate water during periods of non-use, however, an additional pump will be necessary to pressurize this water. This option has additional expense and uses valuable floor space. It is clearly a response to a well that lacks normal capacity.

Seasonal Changes In Well Yield The yield of a point well can be effected by drought and can also change with time due to clogging of the well screen and development in the upstream watershed. To reduce the risk of low water table effects the well point should be installed significantly below the anticipated seasonal low water table. It is not uncommon to have a 5-10 foot variation between the spring and fall groundwater levels. In order to maintain suction, the entire well screen must always be below the water table. If the water table drops below the well screen, the water pump will "loose it prime" and will no longer be able to raise the water out of the well. The seasonal high water table can be determined by soil experts based on the color profile of the soil. It is generally not possible to determine the seasonal low water table.

In addition to loosing prime, pumps for points wells are limited relative to lifting water or "suction lift". See page 4 for a further discussion relative to the limitation inherent in pumping water by "suction lift."

Examples of pollution hazards to your well include the application or inadvertent spillage of fertilizer, pesticides, and inappropriate disposal of old crankcase oil, anti-freeze or solvents, or waste salt brine from water softeners. Thus the use of chemicals in your backyard or that of your uphill neighbors may negatively affect the quality of the groundwater recharging your point well.

Tests for many of these chemicals involve complex and costly laboratory procedures. Thus the best and least costly approach to protect the drinking water quality of your point well is prevention of pollution rather than treatment after the fact. Be careful with respect to the use and disposal of chemicals near and upstream of your well or the wells of others.

The following protective distances are required or recommended when locating a point well for a private single family home:

a) Surface water and drainage culverts should not pass within 25 feet of a point well; 50'+ is recommended.
b) Animals should not be penned or tied within a minimum of 20 feet of a point well;75'+ is recommended.
c) Leach fields and septic tanks shall not be located within 75 feet of a point well.
d) Point Wells should not be located within 50 feet of the right-of-way line of roads, preferably more.
e) Point Wells shall not be placed within 75 feet of adjacent property which you do not control. (See RSA 485-A:30-b). If placement is made necessary within 75 feet, a "standard release form" is required to be signed by the well owner and given to DES, the town health officer and the registry of deeds. Since most zoning codes require a 10 foot setback from adjoining property, this distance is effectively 65 feet.
See fact sheet WD.-WSEB-21-4.
f) A point well should not be placed in locations subject to ANY flooding unless the immediate (25 feet radius) vicinity of the well is built up above the highest flood level.

First no matter how perfect the pump's vacuum, water can not be raised by suction more than approximately 32 feet at sea level. As a practical reality, conventional centrifugal pumps can only raise water by suction, 20-25 feet. Where the water table is deeper than 25 feet below the centerline of the pump, conventional pumping equipment will not work. A "deep well" packer jet pump mechanism can be installed, however, a larger vertical casing/well screen is required which is more expensive.

The second condition occurs if the vacuum is lost by air entering the wellpoint through leakage at the piping joints or because the water level is below the screen of the well point.

The intent of the pump test is to develop an equilibrium between the amount of water being pumped out of the point well and the amount which is replenished naturally from the ground. The discharge should be piped at least 200 feet from the well, and downhill, to prevent recycling or "double counting" of the available water. When first beginning, do not run this dirty water through your plumbing if it can be prevented.

If the drawdown in the well is at a relative maximum depth and has stabilized, this can be considered as the maximum safe yield of the well for that season of the year. This test should be run, in the late summer or early fall when the groundwater table is at its lowest. Otherwise, it must be recognized that a lower water table, still above the screen, will further reduce the well's yield.

To disinfect a point well set aside 10-30 gallons of clean water in a clean trash can. Take off the point well cap; add 1-2 quarts of hypochlorite. Then pour the clean water into the 2.5" +- well casing so as to disperse the chlorine down to the well screen. One gallon of 5.25 percent sodium hypochlorite (common store bleach) in 1,000 gallons of water will provide a good disinfecting solution of 50 parts per million (ppm). Run each faucet in your home until a chlorine smell is detectable. Close the faucets and allow the chlorine to stay in the well and the plumbing 12-24 hours.

For persons desiring to use the DES laboratory, there is a $10 fee for a bacterial test and a $75 fee for "standard analysis." Only agency sampling containers can be used. The time to process the standard samples is approximately three weeks in the summer and two weeks otherwise. Different containers are required for sampling radon gas, industrial solvents and hydrogen sulfide odor.

Sampling containers can be obtained from the Laboratory Services Unit. See DES fact sheet WD-WSEB-2-1 for a discussion of which water quality factors to test in private well. We recommend that a bacterial sample be taken on an annual basis for point wells in view of their shallow construction and once every 5 years for chemistry.

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