Triangle is unincorporated Prince William County, supplied by Prince William Water from the Occoquan Reservoir, with permits from the county's Building Development Division; gas depends on the address, since Columbia Gas of Virginia and Washington Gas both operate in the county. Plumber Washington DC Pros is a free referral service, not a plumbing company. Call the number on this page to be connected with a local plumber in Triangle.

Plumbing services in Triangle
Next to Quantico and the forest park
Triangle is a census-designated place in southeastern Prince William County, about 30 miles from downtown Washington, with 9,589 residents in the 2020 Census. It is wedged between the Town of Dumfries, Prince William Forest Park and Marine Corps Base Quantico, and it is home to the National Museum of the Marine Corps. Housing here is mostly newer, with a median build year around 1999.
What newer homes need
Houses from the late 1990s and 2000s usually have modern supply piping, so calls lean toward water heaters at or past their expected service life, tankless conversions, fill valves, faucet cartridges, shower valves, garbage disposals and sump pumps. Hose bibs and pipes in exterior walls can still freeze on the coldest nights.
Prince William Water
Prince William Water names Triangle among the eastern Prince William communities it supplies with Occoquan Reservoir water treated at Fairfax Water's Frederick P. Griffith Jr. plant. Treatment uses ozone as the primary disinfectant, and the utility says chloramine is used in the distribution system for most of the year, with a switch to free chlorine in spring that can briefly change taste and odor. It describes its East and West systems as moderately hard, defining that as 61 to 120 mg/L. Virginia American Water also runs a separate Prince William system in the county, so if you are unsure, check the name on your water bill.
Prince William Water locates its lines from the main through the meter box; lines and connections on private property are the owner's responsibility. Its service line inventory found that every distribution line and service line it owns and maintains is non-lead, and customers are responsible for any lead in their own home plumbing. Customer service is (703) 335-7950; emergency dispatch is (703) 335-7990, which also handles sewer cleanout cap replacement.
Sewer and backflow
Prince William Water also provides sewer service. If a drain backs up, a missing or broken cleanout cap in the yard is worth checking, and the utility can be reached at its dispatch number; a clog or break in your house drain or lateral is a plumbing call. The utility runs a cross-connection control program to keep backflow out of the distribution system.
Permits for water heaters
Prince William County's Building Development Division (5 County Complex Court, 703-792-6930) issues gas, plumbing and electrical permits. Putting a gas tankless water heater into an existing home needs a gas permit, plus a plumbing permit if water piping is extended more than 10 feet or the pipe material changes.
Gas safety
Columbia Gas of Virginia and Washington Gas both operate in Prince William County, so check your gas bill for your utility. If you smell gas, leave the house first, then call 911 and your gas utility's emergency number from outside.
Triangle versus the District
Washington's housing is decades older and served by DC Water. Triangle's newer homes are on Prince William Water and county permits. Call with your street and what you are seeing, and you will be connected with an independent plumber who sets price and timing with you.
Common questions in Triangle
Where does Triangle's water come from?
Who handles a broken sewer cleanout cap in Triangle?
Are there lead service lines in Triangle?
Do I need a permit for a gas tankless water heater in Triangle?
Nearby cities and towns
Sources
- Wikipedia: Triangle, Virginia
- Prince William Water: Water quality how-to
- City-Stats: Triangle housing
- Prince William Water: Water quality report (PDF)
- Prince William Water: Residential customer FAQ
- Prince William County: Gas-fired residential tankless water heater permit guide (PDF)
- Prince William County: Building Development Division
- Prince William County annex, Northern Virginia Hazard Mitigation Plan (PDF)
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