Water Quality FAQs

Is the water safe to drink and cook with? How would I know if it’s not?

  • Yes. We perform 500,000 laboratory tests per year on our water. We collect samples from both of our water filtration plants (WFP) and from 90 different locations spread throughout in our distribution system.
  • If we had reason to believe the safety of our water was comprised, we would immediately issue a public notification via the news media, our own social media, and our website. 

Why does my water taste/smell like chlorine (or bleach, or a swimming pool)?

  • We add chlorine to the water to protect against microbial contamination as it travels from the WFP to your home or business. Average annual chlorine concentration in the distribution system can be found on our annual report.
  • We adjust chlorine seasonally and to respond to river conditions, so customers may on occasion notice the odor changes. For example, an increase from 1.0 mg/L to 1.5 mg/L may be noticeable to some customers but is still within the normal range.

Why does my water taste/smell earthy/musty?

  • Seasonal changes to the river can include algae that produce taste and odor causing compounds. We monitor levels carefully for geosmin and MIB, which are common in our Patuxent reservoir and not harmful at the levels we detect.

Why does my water taste/smell sulfur/rotten eggs? Why does the water smell like a sewer, could be it be cross-contamination from the sewer system?

  • Cross contamination with sewer is extremely unlikely because drinking water is highly pressurized to prevent infiltration.
  • If you are noticing a sewer or sulfur smell in the COLD water from ALL FAUCETS in your home, please call 301-206-4002. A useful way to check is to take a clean glass and fill it with cold water from the tap, then walk into another room and check the odor again.
  • If you are noticing the odor in the hot water only, please check your water heater for maintenance instructions. Water heaters need to be drained periodically, even if it is new. Instructions may vary, so please check the manufacturer and model specifications.
  • If you are noticing the odor in only specific sinks, check the p-trap under the sink

What is the pink/orange/black slime/mold that builds up near faucets/drains/toilet?

  • Airborne and environmental molds and bacteria like to grow on damp surfaces, so it’s common to see this type of buildup in bathrooms and around kitchen sinks. We recommend using bleach-based products for cleaning.

Why is my water cloudy/milky?

  • Dissolved air in water can cause cloudiness, especially in the winter. Cold water can hold a lot of dissolved oxygen, and when the water exits your faucet at room temperature, the oxygen forms tiny bubbles that make the water appear cloudy or milky.
  • Fill a clear glass with COLD water and wait a minute for the glass to clear. If the cloudiness clears from bottom to top, the cause is air.
  • If the water does not clear after a few minutes, or clears from top to bottom, or you see particles collecting at the bottom of the glass, please call 301-206-4002.

Can I get my water tested for lead?

  • Absolutely. Lead testing samples are collected by the customer in order to capture the ‘worst-case scenario’ of stagnant water, so we’ll ship bottles and instructions to your house. Customers will fill two bottles with their kitchen tap water, fill out the accompanying paper work, and drop off bottles at FedEx for return. We’ll send the results to you via a report in the mail in about three weeks. We charge $29.48 to cover the cost of the shipment.

Why is my water discolored? Is it safe to drink?

  • Yes, discolored water is safe to drink, but we apologize for the occurrence and ask that you call 301-206-4002 to report. We will dispatch a technician to flush the nearest fire hydrant to clear out the discoloration.
  • Our distribution system is largely made of up of iron pipes, so disturbances to the system (such as construction, main breaks, or water re-routing) can cause rusty-colored water. Note that it takes very little iron (0.2 mg/L) to discolor water and there are no adverse health effects associated with iron in drinking water.
  • Visit our webpage on discolored water and flushing guidance.

Why does my washing machine smell?

  • Washing machines are damp environments that can attract airborne bacteria or mold. We recommend leaving the hatch open when it’s not in use, and running a cycle with just vinegar periodically to disinfect. Check the manufacturer’s instructions for maintenance.

Why does my hot water smell?

  • Water heaters can attract sulfur-reducing bacteria, which cause a foul odor. We recommend fully draining your water heater annually, even if it is relatively new. Check the manufacturer’s instructions for maintenance.

Do you test for harmful algal blooms?

  • Yes, we test for harmful algae (also known as cyanobacteria) at both plants in the raw and treated water from summer into the fall.

Do you test the water for pesticides?

  • Yes, we routinely test the water at our filtration plants for a range of synthetic organic compounds, including numerous pesticides. The results of those tests are available in our tap analysis report.

Why does the water taste metallic?

  • Oftentimes customers can interpret typical minor changes in chlorine in a variety of ways – for example, as metallic, acidic, or medicinal – but if you are concerned that the taste or odor has changed significantly, please call 301-206-4002.

Why is the water in my bathtub green/blue?

  • Lighting and background color can significantly affect the way customers perceive color of their drinking water. Bathrooms oftentimes have bright lighting and with different bathtub colors and shades, this can make a full tub of water appear blueish or greenish. If you’re concerned about the color of the water itself, fill a clear glass with water and hold it against a sheet of white paper in natural (outdoor) light.

Do you test the water for emerging contaminants?

  • We participate in a program called the Unregulated Contaminated Monitoring Rule (UCMR), which targets specific contaminants under evaluation as emerging threats. Additionally, our scientists and engineers keep an eye on relevant research and available monitoring techniques to determine if and what we should consider for additional testing.

Is water safe for my pet, including fish?

  • We treat our water to meet EPA specifications for human consumption; pets, particularly fish, may be different. Please contact your vet if you are concerned about your pet’s health.
Last Modified: