Gray/Grey/Galley Tank Grey Tank Sanitation Toilet

Two grey tanks?

Q: It appears I have three tanks, a black and two grey tanks? What goes into each one?

A: Normally 3 tanks, a black tank, and 2 grey tanks(with one known as galley tank), that being said, black is toilet and two grey tanks are for kitchen sink, bathroom sink, bathroom shower/tub, dishwasher and washing machine(last two you might not have), then it is split with one being kitchen sink(galley tank) and the bathroom sink/bathtub/shower). At least all of the RVs I am seeing on a daily basis, those are the common setups.

Freshwater Tank Grey Tank Sanitation Sanitize Water Water Systems

Sanitation of Freshwater System

Q: How do I sanitize my freshwater system, tanks, lines, etc.

A: Drain the water heater – Caution: Never drain the water heater when it’s hot or under pressure.

  • Turn off the water heater.
  • Run water out of your hot water faucets until the temp is low enough to not burn you.
  • Go to the outside compartment where the water heater is located. The drain plug, or petcock is usually located in the bottom left hand corner. Remove the plug and open the pressure relief valve on top of the water heater to assist in draining.
  • Let it drain completely.
  • I like to leave on or turn on my water heater bypass and not put bleach into that tank, since it will heat water, it will kill any bacteria in there so I don’t feel the need to put bleach water into my water heater tank.

 Drain other tanks and lines

  • Locate the low point water line drains. It may take a while to find them but they are there.
  • There will be one for the hot and one for the cold water lines. This is the lowest point in the RV water system.
  • Open these and drain the water out.
  • Find the drain for the fresh water holding tank and drain it also.
  • At this point you can turn the water pump on for a moment to force any remaining water out. Do not let the pump continue to run once the water stops draining.

Close all of the drains.


  • Using a quarter cup of household bleach for every fifteen gallons of water your fresh water tank holds.
  • Mix the bleach, with water, into a one-gallon container and pour it into the fresh water holding tank. Do this as many times as needed for each 15 gallons of water your fresh water tank will hold. Example: If you’re freshwater tank is 45 gallons, do this 3 times. You will want a funnel to pour this into the fresh water tank opening.
  • Fill the rest of the fresh water tank with regular tap water using a food grade hose, not your normal run of the mill garden hose.
  • Turn the water pump on, open all hot and cold faucets and run the water until you smell the bleach at each faucet.
  • Close the faucets.

Let it sit for at least 12 hours.

Drain the entire system again and re-fill the fresh water tank with potable water. Open all of the faucets and run the water until you no longer smell any bleach. It may be necessary to repeat this process again to eliminate all signs of bleach from the water system.

Once all done and you don’t smell any more bleach, you’re good to go.

Black Tank Grey Tank Sanitation

Tank Dump Locations

Q: Where can I dump my tanks?

A: Go to and search.

Black Tank Grey Tank Sanitation

RV Dumping of tanks

Q: Will a septic truck come to a house to empty rv tanks? Has anyone had this done? What should it cost?

A: Give a local one a call and see, it has been known to happen but the cost varies.

Black Tank Grey Tank Sanitation

Open Tank valves all of the time?

Q: Should I keep my grey and/or black tanks open when at a full service campsite?

A: No, never, you don’t want the poop mound in your black tank and that is what you will get if you leave the black tank open. Grey tank you need the contents of it to flush out the sewer hose when dumping it.