Flushing holding tanks

[bounder-andy]

I'm new here and first time owner of a Bounder motor home. Today I took the RV to a camp ground to empty the two holding tanks. Not sure I did it right. After hook up to dump station I drained the black water first then gray water. This unit has a San Flush system at least I think is called that. Any way I hook up a water hose the a blue fitting/adapter to flush the black tank. I let it run for about three minutes with the dump valve open. I noticed that when the water was on this blue thing had a small hole and water was coming out of it. What is this blue fitting/adapter and did I flush the tanks right. Is the flush fitting for black water only and do you need to flush gray water tank. Thanks for the HELP!

[Ray,IN]

Hi Andy,
The first rule of keeping your black tank running free when dumping is to begin with about 5 gallons of water in a freshly emptied tank. This reduces the risk of solids causing a build-up, the main cause of black tank problems. You may use the sani-flush to add that 5 gallons. Try to dump only when the tank is at least 3/4 full. If you must dump when it is only 1/4 full, add water to make 3/4 if possible. The weight of all that water will push solids out of the tank and make flushing it less of an issue. When using the sani-flush, close the tank dump valve and let the sani-flush fill the tank about 1/2 full, then dump again. This should remove remaining solids and sediment.
That hole leaking water from the "blue thing" is probably a anti-siphon device to prevent water from flowing backwards from the tank into the water source.

[OneRVer]

Yes you did it right. Black first then gray. Most RV have the Sani Flush on the black tank but I suppose some might have on the black and gray. A three minute flush should do the trick. I have, on rare occasion, left both black and gray valves open and back flushed the gray tank. However I do make sure the black tank is clean before I do so.

[RickO]

Welcome to the forum and congratulations on your new rig!

As already mentioned, you did fine in your first tank dump and got some good advice although I would add a couple of points.

I would hold off flushing the grey tank until after doing the black tank dump and san t flush a couple of times with the black tank. Then I would dump the grey tank.

I add about 1/4 cup of Dawn dishwashing liquid to the black tank both when doing the san t flush (valve closed while you refill the black tank to about 1/2 tank or better) and when adding the 5 or 10 gallons of fresh water you're going to leave in the freshly flushed tank. You'll find a lot of opinions on this topic but this seems to work best for us.

I've never heard of a san t flush on a grey tank. They might exist but I've not heard anybody talk about them yet.

NEVER, NEVER (never!) get distracted while using the san t flush with the black tank valve closed. Just think of the infamous scene from Robin Williams RV movie. Don't ask me how I know.

It's a good idea to mix a bleach and water solution in a spray bottle and keep it in your plumbing bay. Spray all connections with it as you hook up your fresh water each time. I also give a little squirt to the sewer hose connections when disconnecting.

Best of luck!

rick

[Rocky Larson]

BTW, yes black tank first then gray, however...I always run the gray for a second or two first. Just to check the connections. Makes for more pleasant surprises.

[RickO]

Quote:

Originally Posted by Rocky Larson BTW, yes black tank first then gray, however...I always run the gray for a second or two first. Just to check the connections. Makes for more pleasant surprises.

Excellent point! Me too.

[Elkhartjim]

One caution. If you add detergent to the tank you must rinse it or the bubbles can give you a false reading on your level gauge.

[Gary RVRoamer]

Quote:

I've never heard of a san t flush on a grey tank. They might exist but I've not heard anybody talk about them yet.

My coach has San T flushers on both tanks. Factory standard. Actually, it is one flush unit with a valve to direct it to one tank or the other. I like having both - the gray tank can get pretty raunchy too!

Also: I don't use the blue thingie - just hook the hose direct to the flush port with a quick-connect.

[OneRVer]

Quote:

Originally Posted by RickO I add about 1/4 cup of Dawn dishwashing liquid to the black tank both when doing the san t flush (valve closed while you refill the black tank to about 1/2 tank or better) and when adding the 5 or 10 gallons of fresh water you're going to leave in the freshly flushed tank. You'll find a lot of opinions on this topic but this seems to work best for us.

Question; What do you mean by "5 or 10 gallons of fresh water you are going to leave in the freshly flushed tank"?

Are you leaving soapy water in your tank while not in use? Just asking. I have never thought of this before but might be a good idea.

[RickO]

Quote:

Originally Posted by OneRVer Question; What do you mean by "5 or 10 gallons of fresh water you are going to leave in the freshly flushed tank"? Are you leaving soapy water in your tank while not in use? Just asking. I have never thought of this before but might be a good idea.

Well, we full time so our tanks are alway in use. But, yes, I NEVER want to leave my black tank empty. After flushing it, I will add fresh water and Dawn.... probably closer to 10 gallons than 5... and I do this by closing the black tank valve and leaving the san t flush running. This works for us because we have a 57 gallon black tank and we never really dry camp.

Rick

[RickO]

Quote:

Originally Posted by Gary RVRoamer My coach has San T flushers on both tanks. Factory standard. Actually, it is one flush unit with a valve to direct it to one tank or the other. I like having both - the gray tank can get pretty raunchy too! Also: I don't use the blue thingie - just hook the hose direct to the flush port with a quick-connect.

Very nice! I love American coaches. They had one at The Rally in Louisville this summer and it was something to see!

[galangmaid]

Well, we full time so our tanks are alway in use. But, yes, I NEVER want to leave my black tank empty. After flushing it, I will add fresh water and Dawn.... probably closer to 10 gallons than 5... and I do this by closing the black tank valve and leaving the san t flush running. This works for us because we have a 57 gallon black tank and we never really dry camp.

Rick
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Rick,
How does the san t flush work in filling the black tank if you have the black tank valve close???

[oldcouple]

Look up the GEO method, good advice. If it has been setting for a while, put about ten gallons in it, two bags of Ice down the toilet, a cup of Calgon if you can find it, Dawn should work as well, and take it on a trip that includes several turn, a couple of hills, and maybe a rough road, not hard to find in any state, about an hours should do it. then go dump it, The gray tank is similar, but hard to put Ice into.

[Elkhartjim]

[QUOTE
How does the san t flush work in filling the black tank if you have the black tank valve close???[/QUOTE]

The San T flush system has spray nozzles in the tank. You may be confusing this system with the fitting that connects to the drain outlet with a water hose connection for back flushing.