Monday, September 25, 2023


This gadget makes draining the fresh water tank quick and easy

We always carry some fresh water in our tank as it is always needed when boondocking. it has also been needed more than once when the water was shut off at a campground or the fill station was closed. But when that fresh water is not-so-fresh after a while and needs draining and sanitizing, where do you drain 40-90 gallons of not-so-fresh water?

Plumbing adapter

Certainly, you can’t just let all that water drain everywhere, particularly in a crowded RV park. You wouldn’t have very happy neighbors or campground staff! We have found a solution that works well for us. We bought a plumbing adapter from a local hardware store that fits over the drain under the motorhome’s fresh water tank and that is threaded to allow a garden hose to be attached. You can find these at any hardware store, but each RV will require a different size.

Photo credit Nanci Dixon

Attach garden hose

We attach our garden hose and from there can drain the water into the sewer connection or, in this case, into the dry, thirsty trees and bushes. The bleach water solution is so diluted it will not harm vegetation. It’s easy to leave the hose on, fill and sanitize the tank, then refill and drain until the bleach smell is gone.

Photo Credit Nanci Dixon

Check with the campground first

As full-timers, we drain and sanitize at least twice a year and sometimes more if the water begins to smell funky. It is always advisable to double-check with the campground to make sure they are okay with draining the water into grass or tree areas particularly if they have any concern over the diluted bleach after sanitizing.

As an alternative when sanitizing or dewinterizing run the garden hose draining the fresh water tank to the sewer opening at a full hook-up site.

Photo Credit Nanci Dixon



  1. Our fresh water dump is a large knife valve thing, so there’s no garden hose hookup. We stop somewhere along the road and open the valve as we drive – if there is any water left. We too, fill the fresh tank and work off that even if in full hookup CG’s. Seems to me that our onboard water pump offers better pressure than the CG offers (with a pressure regulator installed).

        • So, if the chickens in the truck going down the freeway are taking a shower, with no soap, it’s OK for the water (if it’s not dirty) and the feathers to be flying behind the truck, or whatever. Got it. Thanks, Tommy! 😆 –Diane

          • Nice take Diane. I should have made it more clear. The water and chicken feathers are referred to on separate trucks. Water trucks going to construction sites almost always leak water. I have followed “chicken haulers” and have seen feathers a-flying. Neither is a threat to the environment. Fresh water and rain are on a par. But, I loved your ‘story’. I couldn’t have conjured up a better scenario. 🙂

          • Thanks, Tommy. Yeah, I got what you were saying. And I used to see lots of chicken feathers flying when I spent more time on the road. But sometimes my brain just goes to weird places. Take care. 🙂 –Diane

  2. I don’t know. If you travel, you do better just working off tank and pump all the time, refill with fresh water as needed, instead of staying hooked up some of the time. Easier to keep track of when tanks need dumping. No stagnant water, no problem.

    • I am of the same opinion… I keep tank moving and only sanitize once a year in Spring defrost. Using the pump 95% of the time also eliminates concerns of high/low site pressure. I have one small mod – intentionally bypassing the pump with a small valve so I can fill fresh tank from inside before leaving the rare hookup site.

    • You could mount a transfer pump, but it’s not advised. If you have double grey, you can safely cross-share them (so shower-bulk goes into always-empty “rear galley”).

    • You can link the two together if you have a 3rd knife valve at the termination pipe. Then, you can just leave your gray and black valves open- letting some gray fill the black tank as you camp. Without physically plumbing them together this is the best way.

    • After I drain the black tank, I leave the black valve open, remove the hose from the sewer and hold the end higher than the tank. I open the grey valve and the grey water runs into the black tank. When I can hear the flow stop, I close the grey valve and raise the hose up and down to force water in it back and forth into the black tank. (don’t let the hose end get lower than the top of the tank). Hold up the middle of the hose and inset the end back into the sewer and dump the black. I repeat this 2 or 3 times until both tanks are empty. Each time the black water gets clearer.

  3. Draining the sanitized water with bleach in it will likely kill the vegetation.
    Bleach permanently kills grass by decreasing the soil pH to a point where no plants can live or develop in the area where it is sprayed. Applying a bleach solution to places such as driveways, between pavers, pebbles, and gravel can cause the soil to become very acidic, thus eliminating vegetation.

    • Don’t most municipal water supplies use some form of chlorine (bleach)
      to sanitize the public water supply? That water is used by millions of homes to water the grass.

    • Thanks for your comment. We have also used the hose to run the water down the sewer at full-hook up sites. I added that to the article.

  4. I you have hookups run all the left over water down the toilet so it can help keep the black tank flushed out. As a weekender I do this with any left over water before heading to the dump station.

  5. I would think the campground may object to more than draining bleach water, how about the 180 gallons of water used in the process? Then refilling the tank again.


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