Does Washington DC Have Hard Water?

Does Washington DC Have Hard Water?

If you live in Washington DC, you may have noticed that your tap water tastes a little different from what you’re used to. You may be wondering – Does Washington DC Have Hard Water?

Washington DC tap water has a hardness of 70 to 120 parts per million or 3 to 9 grains per gallon which is considered moderately hard. This is due to the high concentration of calcium and magnesium ions in the Potomac River where the city gets its drinking water.

In this article, we’ll explore the hardness of Washington DC’s water and what you can do about it.

Read my article about water hardness in other cities.

Does Washington DC Have Hard Water?

How hard is Washington DC's tap water?

Washington DC’s water has a hardness of 115 milligrams per liter (mg/L), which is the same as 115 parts per million (ppm). This makes it moderately hard, according to the United States Geological Survey (USGS).

When converted to grains per gallon (gpg), Washington DC’s water hardness is 6.7 gpg.

City Average Hardness Calcium Carbonate mg/L Average Hardness Grains per Gallon Zip Code
Washington DC 115 ppm 6.7 gpg 20001 | 20002 | 20003 | 20004 | 20005 | 20006 | 20007 | 20008 | 20009 | 20010 | 20011 | 20012 | 20015 | 20016 | 20017 | 20018 | 20019 | 20020 | 20024 | 20032 | 20036 | 20037 | 20045 | 20052 | 20053 | 20057 | 20064 | 20202 | 20204 | 20228 | 20230 | 20240 | 20245 | 20260 | 20307
Norfolk 47 PPM 3 gpg 23503 | 23513 | 23518 | 23505 | 23504 | 23508 | 23502 | 23511 | 23509 | 23510 | 23523 | 23507 | 23517 | 23551
Virginia Beach 58 ppm 3 gpg 23464 | 23462 | 23454 | 23452 | 23456 | 23455 | 23451 | 23453 | 23457 | 23460 | 23459 | 23461
Arlington 120 ppm 7 gpg  
Chesapeake 41 ppm 2 gpg 23322 | 23320 | 23323 | 23321 | 23324 | 23325
Newport News 81 ppm 5 gpg 23608 | 23602 | 23606 | 23601 | 23607 | 23605 | 23603
Fairfax 127 ppm 7 gpg 22030 | 22033 | 22031 | 22032 | 22035
Richmond 64 ppm 4 gpg 23223 | 23234 | 23225 | 23224 | 23220 | 23235 | 23222 | 23227 | 23236 | 23237 | 23226 | 23221 | 23230 | 23219 | 23173 | 23250
Roanoke 143 ppm 8 gpg 24018 | 24012 | 24019 | 24017 | 24014 | 24015 | 24013 | 24016 | 24020 | 24011
Lynchburg 48 ppm 3 gpg 24502 | 24501 | 24503 | 24504
Blacksburg 55 ppm 3 gpg 24060
Winchester 79 ppm 5 gpg 22602 | 22601 | 22603
Harrisonburg 60 ppm 4 gpg 22801 | 22802 | 22807
Danville 72 ppm 4 gpg 14540 | 14541
Table – Water Hardness Values – Cities in Virginia

Learn about water hardness in these cities:
Does Orlando Have Hard Water?
Does Portland have hard water?

Virginia Water Hardness

In Virginia, the source of drinking water varies depending on where you live. Some people get their water from surface water sources such as rivers and lakes, while others get their water from underground sources such as aquifers.

The hardness of Virginia’s water varies across the state. According to the Virginia Department of Health, the water hardness ranges from 1 to 20 gpg.

What is Hard Water?

Hard water is water that has a high concentration of dissolved minerals, such as calcium and magnesium. The USGS defines water with a hardness that is between 60 and 120 ppm as moderately hard.

The following table shows the USGS rating for water quality and hardness concentrations:

Hardness (ppm) Classification
0-60 Soft
60-120 Moderately Hard
120-180 Hard
>180 Very Hard

What are the Problems Caused by Hard Water?

Hard water can cause a number of problems in your home. It can leave spots on dishes, glasses, and shower doors. It can also cause soap and detergent to be less effective, making it more difficult to get your clothes and dishes clean. In addition, hard water can cause scale buildup in your pipes and appliances, reducing their lifespan and efficiency.

Who is Washington DC’s Water Provider?

The water in Washington DC is provided by the District of Columbia Water and Sewer Authority (DC Water). DC Water serves more than 600,000 people in the District of Columbia, including households, businesses, and government facilities.

Where Does Washington DC Water Come From?

Washington DC Drinking Water Map

Washington DC’s water comes from the Potomac River. The water is treated at the Washington Aqueduct, which is operated by the US Army Corps of Engineers. The Washington Aqueduct provides water to both Washington DC and parts of Virginia and Maryland.

Is Washington DC’s Tap Water Treated?

Yes, Washington DC’s tap water is treated to remove impurities and ensure that it meets safe drinking water standards.

DC Water buys clean water from the Aqueduct which is run by the U.S. Army Corps of Engineers. The Aqueduct uses treatment plants to filter, clean, and make the water safe to drink. They follow all the rules made by the U.S. Environmental Protection Agency (EPA) to make sure the water is safe and pure.

The treatment process includes the following steps:

  1. Screens: These remove large debris like branches and scrap wood from the raw water.
  2. Pre-Sedimentation: Large particles in untreated water settle out naturally.
  3. Coagulation: Chemicals called coagulants are added to the water to make particles stick together, creating larger, heavier particles.
  4. Sedimentation: These larger, heavier particles settle to the bottom of sedimentation tanks.
  5. Filtration: Gravity filters made of hard coal, sand, and gravel remove smaller particles still remaining in the water.
  6. Fluoridation: Fluoride is added to the water to protect teeth as recommended by the American Dental Association.
  7. Corrosion Control: Chemicals are added to adjust the water’s pH and prevent corrosion in pipes.
  8. Primary Disinfection: Chlorine is added to the water to kill potentially harmful organisms before the water leaves the plant.
  9. Secondary Disinfection: Ammonia is added to the water to create chloramine, which helps maintain disinfection in the distribution system.

Quality of Washington DC Tap Water

Overall, Washington DC’s tap water is considered to be of good quality and safe to drink. However, there have been some issues with contamination in the past. In 2018, for example, elevated levels of lead were found in some homes due to lead service lines. DC Water is working to replace these service lines to ensure that the water is safe.

How Much Water Does Washington DC Use Each Year?

According to data from DC Water, the water utility serving Washington DC, the city’s average daily water consumption is around 100 million gallons per day. However, this number can fluctuate depending on the time of year and weather conditions. During the summer months, water usage tends to increase due to higher temperatures and more outdoor water usage.

While this may seem like a lot of water, Washington DC has implemented several water conservation initiatives to help reduce its overall water usage. These include low-flow showerheads and faucets, dual-flush toilets, and rebates for homeowners who install water-efficient appliances.

Virginia Water Use and Consumption in Statistics

Virginia’s water consumption varies widely throughout the state, with some areas experiencing higher demand than others. In 2015, the Virginia Department of Environmental Quality reported that the state used an average of 3.75 billion gallons of water per day. Of that total, approximately 50% was used for power generation, while the remaining 50% was used for public water supply, irrigation, and other purposes.

One of the biggest challenges facing Virginia’s water supply is ensuring a sustainable water supply for future generations. Population growth and increased development are putting a strain on the state’s water resources, and it is essential to take steps to conserve and protect these resources.

What Can I Do About Hardness in My Water?

If you are concerned about the hardness of your water, there are several steps you can take to address the issue. One of the most effective ways to combat hard water is to install a water softener. A water softener works by removing the minerals that cause hardness, such as calcium and magnesium, and replacing them with sodium or potassium ions.

Other methods for treating hard water include reverse osmosis and distillation. These methods remove minerals, bacteria, and other contaminants from the water, providing a clean and safe drinking water supply. However, they can be more costly and require more maintenance than a water softener.


Washington DC’s water has a moderate level of hardness, ranging from 70 to 120 parts per million or 3 to 9 grains per gallon. In addition to discussing Washington DC’s water hardness, we’ve explored the sources of the city’s water, the treatment methods used to make it safe for drinking, and the quality of the water. We’ve also discussed the water hardness in Virginia and provided information on what you can do to address hard water issues.

Boch Richard

Richard Boch is a chemical engineer responsible for designing water filtration systems for industrial and residential customers. He has more than 20 years of experience with ion exchange, activated carbon, and reverse osmosis. Richard's expertise has made him a go-to source for municipalities and businesses looking to improve their water quality. When he's not working, Richard enjoys spending time with his wife and two young children.

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