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Well Drilling and Water Testing in NH

Updated 2026-10-10 · 6 min read

How NH wells are drilled and licensed, septic setbacks, what NHDES says to test for and how often, plus shock chlorination, flood and drought advice.

Drilled wells and dug wells

Most NH homes on a private well have one of two types. According to NHDES, bedrock wells (also called drilled or artesian wells) are the most common. Steel or plastic casing runs from the surface down into solid rock, and below that is an open hole in the bedrock. Water comes in through fractures in the rock. NHDES says most household bedrock wells are 200 to 500 feet deep, some go past 1,000 feet, and the median is about 400 feet.

Dug wells are usually 3 or 4 feet across and not much deeper than 15 feet. Older ones are lined with fieldstone; newer ones use interlocking concrete tiles (NHDES DWGB-1-16). Water quality differs too. Arsenic and radon, radium and uranium are fairly common in bedrock wells, while dug wells more often have iron, manganese and low pH that can corrode plumbing. Dug wells are more prone to running low in a drought (NHDES DWGB-1-4).

Who can drill a well or install a pump

Under RSA 482-B:5, anyone in the business of building wells or installing pumps needs a license from the NH Water Well Board, renewed every year. A water well contractor license covers drilling, digging, well development such as hydrofracturing, and decommissioning old wells. A pump installer license is needed to install or replace a well pump. NHDES notes that licensed plumbers and electricians may repair and service well pumps but need a pump installer license to install or replace one.

RSA 482-B:12 lets a person build a well on their own property for their own permanent residence, but they still have to file the well record and follow the board's rules. Check any contractor with NHDES's licensed contractor search. Our licensing guide covers other trades.

Where the well can go

The Water Well Board's rules, We 600, set minimum distances for new wells. For a typical home:

75 feet from a septic tank or leach field for a system designed for up to 750 gallons per day (We 602.07). Larger systems need more distance.
A protective well radius that generally has to stay on your lot, on a recorded easement, or on land that can't be developed (We 602.08). NHDES describes this as 75 feet from property lines for a single-family home (DWGB-1-2).
50 feet from surface water, a sewer line or a state highway right-of-way, and 75 feet from a public road surface, livestock pens, and fertilizer, manure or salt piles (We 602.09). Dug wells need 100 feet from livestock pens and can't go in areas prone to flooding.
If a septic system is planned or built, the driller has to put the well where the state-approved septic plan shows it, or follow the rules for an alternate spot (We 602.12).

Small lots and setback reductions

When a lot is too tight, the rules allow reduced setbacks with extra construction steps, and often a Setback Reduction Form you sign acknowledging the contamination risk (We 602.13 to 602.16). Ask your driller before you sign. Our septic guide covers the septic side.

Drilling, chlorination and the well completion report

A bedrock well needs at least 20 feet of casing, and the casing has to stick up at least 8 inches above the ground (dug wells, 18 inches) (We 602.22 and 602.31). After building a well or installing a pump, the contractor must chlorinate it to at least 50 parts per million for at least 4 hours (We 602.03).

Within 90 days of finishing, the contractor must file a well record with the board (RSA 482-B:10). It includes total depth, casing details, depth to bedrock, static water level, yield test results and any hydrofracturing. Ask for a copy. Reports go back to January 1, 1984, and you can search them by address on NHDES OneStop (how to find well reports). When you sell, RSA 477:4-c requires disclosing the water system's type, location, malfunctions, installation date and most recent water test.

Low yield: the state doesn't set a minimum yield for private wells, though some towns do. NHDES says a well producing 1 to 3 gallons per minute may work if the casing and storage tanks hold enough water, and recommends a safety device to protect the pump. If a bedrock well gives only a few gallons per minute at 100 to 200 feet, NHDES recommends drilling deeper. Hydrofracturing can often improve a low-yield well (DWGB-1-2).

What to test for and how often

There's no state law requiring a private well to meet a water quality standard, so testing is up to you. NHDES's Water Testing Guidance for Private Well Users (April 2026) lists arsenic, bacteria (total coliform and E. coli), chloride, copper, fluoride, hardness, iron, lead, manganese, nitrate, nitrite, pH, radon, sodium, uranium and four PFAS compounds. Its schedule:

Every year: bacteria, nitrate and nitrite
Every 3 to 5 years: the rest of the list
Before buying a home with a well, if the seller hasn't provided a recent test
After a treatment system is installed, then every 3 to 5 years to make sure it's working
Also test for bacteria after a flood, after any work on the well, and when opening a seasonal home in spring (NHDES DWGB-4-1)

Where to get your water tested

Use a lab accredited by the NH Environmental Laboratory Accreditation Program. The NHDES guidance lists labs that serve well owners, including the state's own NH Public Health Laboratories, which tests private wells for a fee and includes an interpretation with the report. NHDES says bacteria samples must be kept on ice and processed by the lab within 30 hours of collection. Enter your results in NHDES's Be Well Informed tool. For radon, arsenic and treatment, see our radon and well water guide.

Shock chlorination

NHDES's fact sheet Disinfecting a Drinking Water Well walks through the steps. Key points: if E. coli is found, don't drink the water unless it's been boiled for at least 1 minute. First look for how bacteria got in, such as a loose cap or a cracked casing. Turn off power to a submersible pump before removing the well cap. Use unscented bleach, never pool bleach, and check your treatment system's instructions first. You can't use the water for 12 to 24 hours, and you shouldn't retest until all the chlorine is gone, which can take over a week. Flush to a dry area, not into a stream or wetland. A well shouldn't need chlorinating more than once a year; if it does, NHDES suggests getting professional help because there may be a structural problem.

After a flood

EPA's private well flood guidance says not to turn the pump on until the wiring has been checked by a qualified electrician or well or pump contractor, and not to drink or wash with the water. EPA notes that wells more than 10 years old or less than 50 feet deep are likely to be contaminated even without visible damage. The well will need to be disinfected and the water tested for bacteria afterward; EPA suggests testing 7 to 10 days after disinfection.

Drought and low water

NHDES's drought fact sheet lists warning signs: cloudy or silty water, no water, sudden pressure drops or surges, and air sputtering from faucets. If you see these, turn the pump off at the electrical panel so it doesn't burn out, and call a licensed pump installer or well driller early, since wait times grow in a drought. Options include lowering the pump, adding storage, deepening the well or hydrofracturing. Don't connect your plumbing to a neighbor's, and don't have water put into your well except from an approved source by a potable water hauler.

A well you no longer use has to be maintained or decommissioned, and NHDES says state law requires a licensed water well contractor to seal it (DWGB-1-7).

Bottom line

Hire a licensed well contractor, keep the well completion report, and test on the NHDES schedule. For trenching and water lines, see excavation contractors, and for treatment equipment and plumbing, see plumbers.

This guide is general information, not legal or medical advice. Rules change and towns can add their own, so confirm details with NHDES's Water Well Program and your town.