What is Grey Water?

Grey water is non-potable water which has been used within sinks, tubs, dishwashers and for laundry. This water normal will contain minerals from detergents, dirty, or human fluids other than fecal. The Grey water will usually contain little to no pathogen like black water. This makes it safer to handle and gives it the possibility of reuse and recycling.

Grey water can become unsafe if it is left untreated in a holding tank as in an RV. This will vary based upon a few conditions such as tank size and atmospheric temperature.

Household vs RV

One of the biggest notable differences would be the holding tank. In a household, all plumbing moves wastewater (black and Grey) collect in the same location, either a septic system or a public sewer system. The Grey water is used in homes is mixed with black water. This reduces the options for reuse.

  • Public ~ Wastewater is contained in the sewer lines and transferred to a water treatment facility. At the facility, the wastewater is treated and separated. Grey water is treated to be returned to the water system or reclaimed for other uses.
  • Septic ~ In a septic system the wastewater is transferred into a holding tank where fecal matter settles to the bottom and the Grey water rises to the surface. Septic tanks will need to be pumped for the waste to be transported by trucks to a water treatment facility. Some systems the Grey water is drained off the surface distributed into a leach field.
  • RV Tanks ~ RVs have separate holding tanks black and Grey waters. Each tank has separate plumbing along with separated discharges. This tank varies depending on the size of the RV, but are usually between 20 and 60 gallons. Some RVers also use am additional portable tank which adds about another 20 to 40 gallons.

Maintaining Your Grey Water

Maintaining Grey water is much easier than most people would think. Keeping in mind owning an RV is like owning a home. There will be days when you will be doing maintenance. Today is the day. Your grey water and black water systems will need regular maintenance including emptying and treating. You don’t need to get out a purchase a hazmat suit.

One thing you will need is a pair of rubber gloves. I suggest disposal, due to the fact you don’t want to be driving around with dirty gloves in the RV. Gloves should be used for handling hoses and adding chemicals into the tanks.

When emptying the tanks, save yourself some trouble. Empty the black water before the grey. This will help move the contents of the black water. Also, purchase a clear adapter with a flush attachment. This will make it easier to see the flow of the waste and then clear the hoses before returning to storage.

Grey water sitting in the holding tank it may begin to create some odors as the minerals settle. A good idea is to invest in chemicals from an RV store or Walmart to keep the RV smelling clean.

Reusing and Recycling

Reusing and recycling will depend on location along with some location environmental regulations. Although the water may look grey or dirty, it is really safe for reuse and easily recyclable. Reuse is simple as using for watering vegetation or cleaning the toilet in the RV.

Recycling can be a little extra work using filters or clarifying chemical. Once the grey water has been treated appropriately it may be safe for drinking and returned to your fresh water system. Although this is not the best option for safety.


Grey water is nothing to be afraid of. The grey water systems are slightly different depending on the use and location. The use of the grey water within the RV is within its own isolated system. Grey water will contain some different minerals after use. These minerals are usually very simple to control or eliminate for reuse.

Just like owning a home there will always be some work to do with the RV grey water system. While reuse and recycling may take a little additional work, both as safe if used appropriately.

I hope you learned a little about grey water.

Please feel free to comment and share.

Kenneth Sagendorph


  1. Akbar Zaib


    I think reusing grey water will really help to prevent water waste. I can definitely use it for toilet flushing. But for how long we can store grey water?

    • admin


      Grey water storage depends on a number of factors including atmospheric temperature, the container, and what is in the grey water. For example, if the is high it is stored in a dark container. The time will be short. Now if you store it in a light colored container in temperatures just above freezing. The time will be extended. Yes, the reuse of grey water does have an extensive list of benefits especially the reduction of wastewater.

      Thank You for your comments and feel free to share and visit again.

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