Serving the Towns That Surround Lawrence Township
This page covers the six Mercer County municipalities that surround our Lawrence Township home base — Hamilton, Ewing, Trenton, Princeton, West Windsor, and Hopewell Township — and the conditions that shape residential plumbing across the county: when homes here were built, what pipe materials those eras left inside the walls, and which water utility serves which town. The town pages below apply these county-wide facts to each municipality’s streets.
JP Plumbing and Heating LLC is headquartered near the geographic center of the county, on Gainsboro Road in Lawrence Township. We’re family-owned and led by NJ Master Plumber Pedro Tavares (License #36BI01389800).
See How Mercer County Plumbing Conditions Play Out in Your Town
Mercer County’s housing is old by national standards. The median home in the county was built in 1969, and roughly a quarter of the county’s housing stock predates 1950 — nearly 18 percent of it predates 1940. That matters for plumbing because a home’s interior systems — supply piping, drain stacks, water heater, heating plant — belong to the era the house was built, and they age on a schedule.
The county’s development happened in identifiable waves, and each wave installed a different generation of pipe:
The pre-war core. Trenton’s rowhome neighborhoods and the oldest village centers — Lawrenceville, Hopewell Borough, Pennington, downtown Princeton — were built when galvanized steel supply lines and cast-iron drain stacks were standard. Galvanized pipe corrodes shut from the inside over decades, choking water pressure; cast iron deteriorates from the inside out. Homes of this era that were never repiped are running on borrowed time, and many still have galvanized or lead service lines between the street and the house.
The postwar ring. After 1945, development filled in around Trenton — Hamilton’s Mercerville, Yardville, and Hamilton Square; most of Ewing; Lawrence Township’s southern neighborhoods. These homes typically carry early copper supply piping, which is better than galvanized but prone to pinhole leaks as it ages past fifty years, along with first-generation boilers and water heaters that have often been replaced once and are due again.
The suburban expansion. From the 1960s through the 1980s, growth pushed outward into Hopewell Township, West Windsor, and the Route 1 corridor. Copper remained standard, joined later by CPVC. These homes are now crossing the age threshold where water heaters, well-worn valves, and original fixtures fail in clusters.
Newer construction. West Windsor’s later development and infill throughout the county brought PEX and modern materials. These homes have fewer piping failures but the same water-quality and water-heating questions as everyone else — often more acutely, since larger homes work their equipment harder.
Heating fuel history runs on the same timeline. A large share of Mercer County’s pre-1970 housing was built with oil heat. As natural gas mains extended through the county, most neighborhoods gained access to gas — which is why oil-to-gas conversion remains steady work here: buried or basement oil tanks, aging oil-fired boilers, and utility gas available at the curb.
One County, Three Water Systems
Where a Mercer County home gets its water depends on the street it sits on, and the county is divided among three major systems. This affects water chemistry, sediment load, main age, and service-line material — which in turn affects everything from how fast a water heater accumulates sediment to whether a filtration system earns its cost.
Trenton Water Works serves the city of Trenton and portions of four surrounding municipalities — Ewing, Hamilton, Hopewell, and Lawrence. The system’s condition has drawn sustained public attention: following a state DEP report, the mayors of all five municipalities issued a joint statement pressing for improvements. For homeowners on TWW water, system age is not an abstraction — it is the distribution network their service line connects to.
Aqua New Jersey serves parts of Lawrence Township, including the village of Lawrenceville, and other pockets of the county. Aqua has been actively replacing aging water mains in its Mercer territory — including along Route 206 through Lawrenceville — which is direct evidence of distribution infrastructure reaching the end of its service life.
New Jersey American Water serves Princeton, West Windsor Township, and portions of Hopewell Township and Lawrence Township, with resale service to Hopewell Borough. NJAW has committed to removing all utility- and customer-owned lead and galvanized service lines by 2031, as required by New Jersey state law — a mandate that applies statewide and speaks to how common older service-line materials remain in this region.
The practical takeaway: two houses a mile apart in Mercer County can be on different utilities, with different water chemistry and different-aged mains. That’s why we verify the serving utility for each town — and often each street — before making recommendations about water heaters, softeners, or filtration.
See How Mercer County Plumbing Conditions Play Out in Your Town
Each municipality we serve has its own mix of housing eras, pipe materials, and water service. The pages below apply the county-wide conditions on this page to each town’s neighborhoods and streets.
Trenton, NJ Plumbers
Hamilton, NJ Plumbers
West Windsor, NJ Plumbers
Princeton, NJ Plumbers
Hopewell, NJ Plumbers
Ewing, NJ Plumbers
Sources
- U.S. Census Bureau, American Community Survey — Mercer County housing stock (median year built 1969; ~17.9% of homes built before 1940, another 5.5% by 1949; ACS data via Point2Homes)
- New Jersey American Water — Territory Served, Water Service (Mercer County: Hopewell Township in part, Lawrence Township in part, Princeton, West Windsor Township; resale to Hopewell Borough)
- New Jersey American Water — lead and galvanized service line replacement by 2031 under NJ state law
- Municipality of Princeton — Utility Services (NJAW provides water for most Princeton residents)
- Joint Statement of the Mayors of Trenton, Hamilton, Ewing, Lawrence, and Hopewell Township Concerning Trenton Water Works — January 27, 2025 (following the NJ DEP technical, managerial, and financial assessment of TWW; also published by the City of Trenton)
- Lawrence Township — Aqua NJ water main replacement along US Route 206 (Main Street) and Hendrickson Road
- Lawrence Township — Water Service Area Map (street-level utility boundaries: Aqua New Jersey, New Jersey American Water, Trenton Water Works)
- New Jersey Uniform Construction Code — permits administered by each municipality’s construction office
Frequently Asked Questions
Which towns does JP Plumbing and Heating serve in Mercer County?
We serve Lawrence Township — where we're headquartered — plus the six municipalities that border it: Hamilton, Ewing, Trenton, Princeton, West Windsor, and Hopewell Township. Every job dispatches from our Lawrence Township shop on Gainsboro Road.
Which water utilities serve Mercer County?
Three systems divide the county: Trenton Water Works (Trenton plus parts of Ewing, Hamilton, Hopewell, and Lawrence), Aqua New Jersey (parts of Lawrence Township including Lawrenceville, among others), and New Jersey American Water (Princeton, West Windsor, and parts of Hopewell and Lawrence Townships). The boundaries run street by street, so we confirm the serving utility by address.
Why do so many Mercer County homes have low water pressure?
In most cases, age. Homes built before World War II were plumbed with galvanized steel supply lines, which corrode shut from the inside over decades. Roughly a quarter of the county's housing predates 1950, so original galvanized piping — and the falling pressure that comes with it — remains common in Trenton, the older village centers, and pre-war streets throughout the county.
Do I need a permit for plumbing work in Mercer County?
Permits in New Jersey run through each municipality's construction office under the Uniform Construction Code — there's no single county-wide permit office. Water heater replacements, boiler changeouts, repiping, and underground water or sewer work generally require permits and inspections. As a licensed NJ Master Plumber, Pedro Tavares handles permit applications and inspections as part of the job, in whichever town the work is located.
Do you handle plumbing emergencies across Mercer County?
Yes — during our business hours, Monday through Friday 7 AM to 7 PM and Saturday until 2 PM, emergency calls jump the day's schedule. Because we dispatch from Lawrence Township at the center of the county, we reach any of the surrounding municipalities quickly.
Is oil-to-gas conversion common in Mercer County?
Very. A large share of the county's pre-1970 homes were built with oil heat, and natural gas service is now available in most neighborhoods. Converting typically means removing or decommissioning the oil tank, replacing the oil-fired boiler or furnace with gas equipment, and coordinating the utility connection — all work we handle under one license.
Plumbing Services Across Mercer County
Wherever you are in Mercer County, the conditions on this page are running inside your walls — and JP Plumbing and Heating dispatches from the center of the county every morning, trucks stocked to repair, replace, or install on the first visit. Every project runs under the license and personal oversight of NJ Master Plumber Pedro Tavares, the same standard behind our 5.0-star reputation.
Call (973) 932-2368 — Monday–Friday 7 AM–7 PM, Saturday 7 AM–2 PM.