Gaithersburg, Maryland Water Outage Today

Gaithersburg water system at a glance

Washington Suburban Sanitary Commission is the water system EPA lists for Gaithersburg, serving about 1,900,000 people. Customers know it as WSSC Water; the name on your bill is the one to call.

Where Gaithersburg's tap water comes from

Tap water in Gaithersburg starts as surface water. Washington Suburban Sanitary Commission takes it from the Potomac River and Duckett Reservoir Patuxent R and runs it through treatment before it reaches the mains. Treatment points named in EPA's facility list include Potomac Filter Plant and Patuxent Filter Plant. After treatment the water is held in 1 storage tank or reservoir, which is the buffer that keeps taps running for a few hours after a pump or main fails.

The outage angle. Surface water needs a treatment plant running around the clock, so a plant shutdown, a raw-water pump failure or a long power cut at the plant can lower pressure across the whole service area, not just on one street. Boil water notices are more likely to be citywide after that kind of failure than after a single main break.

What causes water outages and low pressure in Gaithersburg

These are the causes that match the record for Gaithersburg, listed roughly in order of how much they matter here.

• Freezing weather. Gaithersburg sees about 97 days a year with a low at or below 32°F, and 16 days at or below 20°F. The coldest morning in the 2015 through 2025 record came on March 6, 2015. The longest stretch with highs that never rose above freezing ran 13 days, ending January 8, 2018. Frozen service lines and meters cause single-address outages, while ground frost and thaw cycles crack older mains and produce the street-wide breaks.
• Flooding and heavy rain. NOAA logged 310 flood, flash flood and heavy rain reports in Montgomery County from 2015 through 2026, and 6 days a year bring an inch of rain or more. High water can wash out the ground under buried pipe, flood pump stations and push treatment plants past their limits, which is why boil notices so often follow a flood.
• Storm-driven power loss. Thunderstorm wind, hail and tornado reports in Montgomery County number 561 since 2015. Pump stations and treatment plants that depend on Pepco run on the electric grid, so a storm that downs power lines can lower water pressure even when no pipe is damaged.
• Younger pipe, different risks. Only 11.2% of occupied homes in Gaithersburg predate 1970 (US 35.5%), so more of the network is newer plastic or ductile iron. Breaks tend to come from construction damage, pressure surges and weather rather than age.
• Digging and utility work. Street projects, fiber installation and excavation near buried pipe regularly cut mains in Gaithersburg with no warning, usually on a day with perfectly ordinary weather.
• One-address problems. A closed valve, a meter swap or a failed regulator can leave a single house dry. Compare notes with a neighbor first; if they have water too, start with your own plumbing.

How weather strains the Gaithersburg water system

Main break season in Gaithersburg runs from late fall into early spring, with the coldest stretch around December through February.

A note on the numbers: they are modeled for the city center and averaged over eleven years, so they show how often Gaithersburg sees each kind of weather, not what any one thermometer read on a given day.

Is Gaithersburg water safe? Boil notices and EPA record

Since 2015, EPA's record for Washington Suburban Sanitary Commission shows no health-based violations.

A boil water notice in Gaithersburg is a separate thing from a violation. WSSC Water issues one when pressure falls low enough for contamination to enter the pipes, after a main break is repaired, or when a routine test comes back positive. The Maryland Department of the Environment (MDE) oversees the process, and the notice stays until clean samples come back, usually a day or two after pressure returns.

What the lead tests and housing age say about Gaithersburg

The most recent 90th-percentile lead result filed for Washington Suburban Sanitary Commission is 0 ppb (2020). The federal action level is 15 ppb, so that result is comfortably below it.

11.2% of occupied homes in Gaithersburg were built before 1970, and lead service lines and solder stayed legal until the federal ban in 1986. After any outage that disturbs the pipes, run the cold tap 30 seconds to 2 minutes before drinking, and ask WSSC Water about its lead service line inventory.

Restoration times for water outages in Gaithersburg

Most repairs of an ordinary main break in Gaithersburg take half a day once the crew is on site. Bigger mains, deep bury and busy roads stretch that to a day or more. With 1,900,000 people on the system, a break on a main that feeds a whole district can leave thousands of homes dry at once, and crews may close valves several blocks away to isolate it.

WSSC Water will post an estimated restoration time for a break that affects many customers; ask for the repair crew's estimate when you call.

Preparing for a long water outage in Gaithersburg

Census figures put the typical Gaithersburg household at about 2.7 people. At one gallon per person per day that is 8 gallons for three days or 38 gallons for a two-week supply.

• 22.1% of homes are in buildings with 20 or more units. Upper floors lose pressure first, and rooftop tanks and booster pumps depend on building power.
• Your water heater tank holds 30 to 50 gallons of clean water. Turn off the power or gas to it first, then drain from the valve at the bottom.
• Fill the bathtub and a few large pots as soon as you hear a break is likely; that water is for flushing and washing, not drinking.

Gaithersburg versus neighboring water utilities

Water outage pages for nearby cities

Rockville, MD · Frederick, MD · Alexandria, VA · Bowie, MD