Well Drilling in Hillsborough County, NH

• Place names here follow the Census Bureau's 2020 county subdivision list for Hillsborough County, which agrees with its current TIGERweb layer: Manchester and Nashua are cities, and every other subdivision, including each name listed under Communities Served, is a town.
• Historical water service: the 1987 USGS report listed Amherst, Hollis, Hudson, Litchfield, Merrimack, Milford, Nashua and Pelham as communities with public-supply wells in stratified drift, said Nashua and Wilton depended mainly on surface water for municipal supply, and said Brookline, Lyndeborough and Mont Vernon had no municipal systems and were served by privately owned dug, driven or drilled wells. That is a mid-1980s snapshot, so check present-day service with the town or water utility.
• Finding a past well record: NHDES says its well inventory was started in 1984 together with RSA 482-B, now has over 135,000 public records on NHDES OneStop, and does not include wells put in before 1984; the New Hampshire Geological Survey, as data steward, handles data entry and quality control. Because a mapped record may not pin-point the well on a given lot, NHDES suggests a Subsurface (Septic) Systems Bureau file review of the site plan, which shows where the well was approved.
• Checking a contractor: NHDES runs a OneStop lookup of licensed well and pump contractors, which its construction FAQ says can be searched by company, by area or by kind of license.

• Drilled bedrock wells with casing seated into competent rock (We 602.22)
• Gravel wells drilled or washed into sand and gravel and finished with open-end casing, a well screen, a gravel pack or perforated casing (We 602.25)
• Replacing a dug well in till; the 1987 USGS report says such wells can usually meet household needs but can be much less reliable in dry seasons
• Submersible pump, pitless adaptor and pressure tank installs under We 702
• Chlorinating a new well, or an existing well when its pump goes in or back in
• PFAS, arsenic and standard water testing following NHDES guidance
• Sealing a replaced or abandoned well (We 604)

• Depth and yield: no typical local depth is quoted here. NHDES's construction FAQ points owners to its Well Completion Report Query, which holds the depth and yield of new wells reported since 1984. A 2002 USGS statewide bedrock study (Professional Paper 1660) drew on those reports, noting that NHDES had accurately located more than 20,000 wells reported since 1984 and that well yields in that database ran from zero to more than 500 gallons per minute.
• Fractures and fault zones: the 1987 report says water in the area's bedrock comes mainly from fractures and cracks, whose number and size tend to decrease with depth, and that the largest stored quantities are usually found in fault zones. It cites bedrock well MKW-147, on the Naticook fault zone in Merrimack, with a reported yield of more than 100 gallons per minute, and it left the extent and expected yields of those zones outside the study's scope.
• Casing in rock: a bedrock well gets no less than 20 feet of casing, installed so that at least 10 feet of it sits in competent bedrock (further if the casing and drive shoe need a deeper seat), and placed so that neither groundwater nor contaminants can get in at its foot or along its length (We 602.22). When bedrock is drilled by air rotary, water must be injected continuously at a rate sufficient to clean the well and prevent dust.
• Gravel wells: in sand and gravel, We 602.25 has the casing stand 8 inches or more above grade (higher in flood-prone areas, enough to keep surface water out, and 18 inches on a public water system well), capped with a sealed cover and grouted outside under We 602.05. For a gravel well, that section starts the grout 5 feet below the pitless adapter and carries it deep enough, by the well's design, that surface water cannot run down along the casing; the allowed grouts are neat cement, cement-sand, high-solids bentonite, and cement-bentonite holding 5 percent bentonite at most. Excavated wells and driven or drive-and-wash wells are outside We 602.05.
• Pump system: We 702.05 requires at least two check valves on a submersible installation, underground service pipe rated for a working pressure of at least 160 psi, a pitless adaptor on domestic wells with a casing inside diameter of 4 to 12 inches, and a supply line buried at least 4 feet deep, or shallower with added freeze protection where bedrock or ledge rules out 4 feet. Wells 6 inches or wider need a torque arrestor on a submersible pump unless the pump hangs on steel pipe or the well has a caving condition; when caving is the reason, double-jacketed wire or wire sleeved from the pump to the pitless adapter is used instead. We 702.04 runs the well wire in conduit from the well to the inside of the foundation wall. We 700 does not apply to pumps installed temporarily to take water samples, test yield or develop yield.
• About this site's estimate: the calculator takes your depth, prices each foot at a band tied to the ground type selected, and adds a catch-all permit line marked as varying by county, plus pump and pressure tank lines unless you switch them off. Those numbers are national, from Angi, HomeGuide and HomeAdvisor, so they are neither Hillsborough County bids nor any New Hampshire fee; the Board's fee rule is summarized in the FAQ.

• Licenses: RSA 482-B:5 makes an annual license a condition of doing business in well construction or pump installation; a license cannot pass to someone else and lapses each June 30. We 302.01 ties a contractor license to building supply, observation, geothermal (open or closed loop) and construction-dewatering wells over 20 feet deep and to technical drilling, and, subject to We 302.02, ties a pump installer license to putting in new or replacement pumps, running pumping tests, and maintaining or repairing pump systems already in service. Licenses are issued to a corporation or other business entity in conjunction with a named qualified individual (We 302.03(a)), and We 302.03(b) says the employees of a licensed contractor or pump installer need no license of their own.
• Work that needs no license: We 302.02 exempts wells of 20 feet or less that temporarily dewater a construction site and the pumps doing that dewatering, as well as exploratory excavations into foundation conditions for a structure. A licensed plumber (practicing plumbing under RSA 153:27, XIV) or licensed electrician (making electrical installations under RSA 319-C:2, III) may maintain and repair existing pump systems. Pumping tests on new wells may use a temporary pump put in by a water distribution system operator licensed in New Hampshire under RSA 332-E or by a professional engineer or geologist licensed in New Hampshire under RSA 310-A, after which only a licensed pump installer may do the final installation. RSA 482-B:17 then carves out two more cases, provided the work conforms to Board rules: an owner, or the owner's agent, repairing or replacing a pump installation on land the owner owns, and anyone who regularly employs a maintenance person whose job includes replacing and maintaining the pump installations on the employer's property, while that employee is doing that work.
• Drilling your own well: RSA 482-B:12 says nothing in the chapter prevents you from building a well on property you own or lease when the well is meant solely for noncommercial farming, or one whose water will serve neither the public nor anyone living anywhere other than your own permanent residence. You still owe the Board the RSA 482-B:10 well record and must follow any applicable rules, and We 801.03(h) lets the owner of such a well sign the completion report.
• Getting licensed: the experience, examination, reciprocity and continuing-education terms are in RSA 482-B:5 III to V and in We 302.05, We 304, We 305 and We 402; among them, RSA 482-B:5 III asks a drilling contractor for one year of experience drilling water wells in crystalline rocks of the Appalachian Region, within the 3 years in the trade the statute requires. The Board decides each applicant's eligibility for the exam and license, according to NHDES.
• Lots on public water: We 602.19 does not allow a private well on a lot served by a public water system if the requirements of RSA 485-A:30-b cannot be met or if the well would breach a subdivision approval under RSA 485-A:29. When both are satisfied, We 602.19(b), citing RSA 362:4, IV and V, says no property owner shall be required to connect to the public system. The bar in paragraph (a) does not apply to closed loop geothermal wells.
• Septic distances: We 602.07 sets at least 75 feet between a well and both the septic tank and the effluent disposal area of any system with a design flow up to 750 gallons per day, reducible to 50 feet for the tank alone if it is sealed and grouted and its soil line is SDR 26 or an equivalent; the rule otherwise determines septic setbacks under Table 1008-4 of Env-Wq 1008.06(b), reprinted in the rules' Appendix C. The contractor locates existing tanks and disposal areas and, when they cannot be seen, may reasonably rely on the owner's information. Distances to roads, surface water, sewers, livestock pens, salvage yards and similar sources are in We 602.09, underground storage tank distances in We 602.11, and the procedure for a site that cannot meet them, including the owner's Setback Reduction Form, in We 602.13 through We 602.17.
• Disinfection: a new well, and any well that receives a new or reinstalled pump, is chlorinated to a minimum of 50 parts per million for a minimum of 4 hours (We 602.03, We 702.02), and that water may not be released into surface water of the state (We 602.04, We 702.03).
• Well record: within 90 days after a well is completed, RSA 482-B:10 has the contractor give the Board a record of it; We 801 sets what the report must contain, who signs it, how it may be filed (including through NHDES OneStop), when a well counts as complete, and the consequences of a late, unsigned or incomplete report. We 602.02 adds a report for each well decommissioned.
• Sealing old wells: an abandoned well is one that is inactive, not maintained under We 603 and not sealed (We 604.03). Its owner is responsible for having it sealed, except that a licensed water well contractor is responsible for sealing a failed borehole, or an abandoned well whose abandonment both resulted from improper well construction and occurred within 12 months of the date of construction (We 604.06). A contractor who completes a replacement well must tell the owner about the We 603 and We 604 maintenance and abandonment requirements for the existing well. We 604.02(b) states that a well shall be sealed only by a licensed New Hampshire water well contractor, and We 604.04 and We 604.05 set out the removal of equipment and the sealing methods for each type of well. We 603.02 gives the options for a well that is unused but not abandoned.

• Bedrock: the 1987 report describes a northeast-southwest structural trend and three belts from east to west: metasedimentary rocks of the Berwick Formation (phyllites, granulites, gneisses and schists intruded by granodiorite and binary granite); plutonic rocks including Massabesic Gneiss, granitic migmatite, granite and binary granite; and metasedimentary rocks of the Rangeley, Perry Mountain and Smalls Falls Formations (quartzite, sandstone, siltstone, shale and mica schist, locally intruded by granite). Among the major northeast-trending fault zones it names are the Naticook, Bower Pond, Nashua, Chase Brook, Campbell Hill-Hall Mountain, Flint Hill and Silver Lake faults.
• Sand and gravel: the report gives saturated thicknesses from 0 or less than 20 feet near aquifer edges to more than 100 feet in the Souhegan and Merrimack River valleys, and transmissivity from less than 2,000 square feet per day across much of the area to more than 8,000 in Amherst, Brookline, Hollis, Hudson, Litchfield, Merrimack, Milford, Nashua and Pelham. Groundwater generally flows from valley walls toward surface waters, which drain the aquifers. Its analytical models estimated that six aquifers, the Amherst-Beaver Brook, Amherst-Milford Souhegan River, Litchfield-Darrah Pond, Merrimack-Naticook Brook, Merrimack-Merrimack River and Pelham-Beaver Brook aquifers, could provide an additional 12 million gallons per day, an analysis that did not weigh low-flow maintenance or the water-quality effects of induced recharge.
• Water quality in 1987: the report found naturally elevated iron and manganese, with 7 of 32 sampled wells over the USEPA recommended limits for both and 3 over the manganese limit only; slightly corrosive groundwater with pH from 5.0 to 7.3; and sodium averaging 24 mg/L, which it tied to highway deicing, with the USEPA recommended sodium limit of the time exceeded at 11 of 32 sites. It also reported groundwater contamination at two USEPA Superfund sites in Milford and Nashua that had shut down municipal and private supply wells.
• Arsenic: NHDES fact sheet DWGB-3-2 (2021) puts at about 25% the probability that a private well in the state contains naturally occurring arsenic above 5 micrograms per liter. The sheet says testing is the only way to find the level because arsenic in water has no color, taste or odor, and links the state's highly fractured bedrock to very different water quality in wells only a short distance apart. When a test is above 5 ppb, NHDES recommends a follow-up arsenic-III test before a treatment system is chosen.
• PFAS: NHDES says PFAS have affected private wells throughout the state, especially in the south, and recommends that all private well owners test for them. Its Saint-Gobain Performance Plastics page traces the investigation to PFOA found in 2016 in a tap water sample collected inside the company's Merrimack facility, whose water came from the Merrimack Village District's network of supply wells, and says airborne transport from the plant was an important pathway for regional groundwater contamination. Saint-Gobain's sampling of water supply wells inside the 2018 Consent Decree Outer Boundary, under way since 2019, has collected drinking water samples from approximately 2,600 properties and identified nearly 1,200 with an exceedance of state water quality standards; as of summer 2026 point-of-entry filtration had been installed at 860 properties, and water main extensions and connections for areas of Merrimack and Bedford that began in July 2024 was substantially completed in 2025.

Amherst · Hollis · Brookline · Milford · Merrimack · Litchfield · Hudson · Pelham · Bedford · Goffstown · New Boston · Weare · Mont Vernon · Wilton · Peterborough · New Ipswich