Tankless Water Heater in Herndon, VA

Herndon conditions

The Town of Herndon runs its own water and sewer utility inside town limits and buys its drinking water from Fairfax Water, mostly from the Corbalis plant on the Potomac River. Fairfax Water's results for that plant show total hardness of about 70 to 185 mg/L, averaging roughly 7.5 grains per gallon, varying with the season. That is moderately hard, so a tankless unit should go in with isolation valves and a flushing schedule.

The median Herndon home was built in 1983, so most houses have a basement or garage heater on gas pipe sized for a tank. For work inside the town, Building Inspections issues building and trade permits, including Plumbing/Gas and Mechanical, with applications sent by email. Properties with a Herndon mailing address outside town limits, for example south of the Dulles Toll Road, fall under Fairfax County Land Development Services.

Gas follows the same split. Columbia Gas of Virginia serves the Town of Herndon, while some unincorporated Herndon-addressed areas are on Washington Gas. The utility on your bill decides which number to call, and it also tells the plumber whose meter and supply pressure the new gas pipe must be sized from. Many houses near the historic downtown have tight basements, so the vent route to an outside wall is worth checking early.

Options compared

Signs to call

• A tank leaking at the base or relief valve
• Error codes or burner shutdowns on an existing tankless unit
• Gradually weaker hot water flow
• White scale on aerators and showerheads

Seasonal notes

Size a tankless unit for winter, when incoming water is coldest and flow at your set temperature drops. Spring brings Fairfax Water's switch to free chlorine, a taste change only. If you smell gas, leave first, then call 911 and, from outside, Columbia Gas of Virginia at 1-800-544-5606 if you are in the town, or Washington Gas at 844-WASHGAS (844-927-4427), option 1, if that utility bills you.