Dried up Black Tank

A friend of mine just bought a used motorhome from an estate sale. The coach has been sitting for two years and the black water tank had not been emptied and had dried up. He has tried my suggestion to pour a quantity of washing soda in it and then fill the tank about half way with water and drive it around and let the water slosh around in the tank to dissolve the solids and clean it.
We also tried my flushing attachment that is built into an elbow that fits on the hose. Neither method has worked so far.
Does anyone have any suggestions ??



Woody

This may require patience and several attemps may be required.
Try this eco-friendly mixture as outlined in this previously posted tip here.

Use hot water to speed up the liquification process.

carson

Thanks for the link Carson, I'll call him tomorrow and we'll give that a try.

Woody

I agree the best method is keep at it, IF the tank drains you are in luck  If the tank does not drain, I have a suggestion but I'll hold it for a bit.

Keep using Washing soda or Dawn Dishwashing liquid (NOT the Anti-bacterial)  Add a biological agent to the tank to encourage cleaning

Tank rinsers come in a few different designs

My rig came with a tank rinser called "The Flusher" Far as I'm concerned that unit belongs in the black tank cause it was a piece of... What goes in the black tank.  I replaced it with "The Tornado" a much nicer unit, but you are no where near ready for that upgrade yet, that comes AFTER you clean the tank

So long as the tank drains there are two kinds of rinse wants... I have one and kind of made a version of the other

The one I bought I wish I had not, it is a flexable hose with pin size "jets" at the bottom, not really very good at all

The one I wish I bought is called "The Twister" this one has a brass "Spinner" on the end with angled jets to spin it. This one stands a decent chance of actually WORKING

The one I made, which for you might be the best, is constructed as follows

About five or six feet of 1/2 inch PVC, a pipe cap and a hose fitting (I used male and use a double female adapter to feed it)

In the side of the cap, in line with the blue line on the pipe, or the printed line on the pipe (pick a line) I drilled a hole, My hole is about 7/32" as.. Well.. That's the drill I grabbed first, exact sice does is not critical but between 1/8 and 1/4 is suggested

I use a combination feed considting of a valve feeding a SPRING check valve feeding a Brass Vacuum breaker feeding the double female hose which feeds the washer (Takes longer to type this thand to put it together)

Now I have a JET I can aim to where it will do the most good.  I can hold it and slowly move it and a jet that powerful (City water is around 80psi) will chew through solid rock if you hold it long enough (i'm not kidding here)


I would use such a wand, and then use the assorted "GEO" methods, and then when parked fill the tank about 1/2 and add biologicals (Ordo-los or Power or any of the enzime/bacteria products, Even common yeast will help)

Rid-ex if you plan on letting it sit for months

Lots of things, all eco friendly.

And if all else fails I'm told there are companies that pressure wash those tanks Somehow.. NOt a job I'd want.

Thanks John,
I have printed your instructions out for him. I don't understand the bit about a spring valve feeding a check valve but maybe he will.

Woody

Ok, check valves are one-way valves, water flows in one direction only,  There are two basic types

one is a spring check, in this there is a faucet washer pushed against a seat by a spring.  The water pushes against the faucet washer and forces itself through the valve so water flows.  Should pressure be lost the valve closes

A vacuum breaker is another device it is a 2-way valve designed so that if there is pressure from water entering the inlet it seals the other inlet (Which is for air) and allows water to flow through but should the water flow stop suddenly Then a vacuum will form, it will then allow air to enter the line "Breaking" the vacuum and again preventing contents of the black tank from entering the water hose.

I use both, in that order, so if water pressure is lost, 1: The check valve closes and stops any possible backflow and 2 the vacuum breaker breaks the result vacuum and drains the want into the tank.

The idea is what the British call "Belt and Braces" we here in the us say "Belt and Suspenders"

Redundant safety devices.

Then there is always mother nature's way. Let the bugs have a feast and clean the tank. I'd suggest that your friend go to the local waste treatment plant and explain his problem to the plant manager. He should ask for a gallon of anaerobic sludge. Dump the sludge in the tank and fill about 3/4+ full of watter. In about 3-4 days, the little critters should have consumed all the dried organic material. Be forewarned that the anaerobic action will produce some methane  gas and he should make sure that the roof vent is clean and open. It will not smell nice either. He should resist the temptation to open the toilet valve during this time, otherwise, the oder will drive him out of the coach. The methane gas will be a hazard, so he should be careful and not smoke around the roof as the gas is vented.

Alternately, he can ask for activated sludge and hook a small aquarium air compressor up to continuously aerate  the mixture  while it is in the tank and let aerobic instead of anaerobic bugs do the job. This will take about twice  as long. The anaerobic critters are not quit as aggressive as the anaerobic ones.

The waste treatment plant folks may even have a been suggestion for him.

Have fun!

Chet18013

Thanks for the reminder of aerobic and anaerobic action Chet. Haven't dealt with that since I was in school.

The anaerobic critters are not quit as aggressive as the anaerobic ones.

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Assume that's a typo.

Thanks for the advice about the anaerobic sludge Chet. I called my friend and he immediately called our local water treatment plant and they said they were not allowed to sell or give away any supplies or materials. Is there anywhere else he can get it ??
He's still fixing the coach up (with my help) so he won't be using it for the next couple of weeks but he would like to take it on a shake down cruise in the near future.

Woody

Well, if you know of a properly working septic tank anywhere that is accesible, dipping out a gallon of the, ah, effluent would probably do the trick. You might find a package of dried yeasts in a hardware store if there are lots of septic tanks in your area - they sell it under various names such as septic tank conditioner or whatever.

Yes Tom, it is. Should be " aerobic is not as aggressive as anaerobic."

Just remember if you use septic tank sludge or one of the additives, it will be anaerobic.

I used to deal with the waste treatment plants and am sure your friend would have better luck with a personal visit. A phone call will always get the stock answer, whereas a visit gives them a face to put with the call. Always go to the manager or superintendent. An operator will not usually take the independent action required to get the sludge sample. Remember go to the sewer plant, not the water plant.

Chet18013

Woody, I should have mentioned this in the previous post. Tell your friend to use warm water when he fills the tank, if he tries the anaerobic sludge suggestion. The bugs like it at about 90 deg F. Cold water will slow them down noticeably.

Chet18013

Go to the hadwe store and get a bottle of ROEBIC Septic Cleaner or Drain Cleaner and pour a half a Bottle in it along with about 5 gal of Tepid water drive it around then in the AM add a bag of Ice cubes  to the Black tank and drive it again a good distance.  By the time youj get home it shuld be all loosened up.  Been there done that.

Thanks Chet and Shayne, I'll pass it along. I talked to him last night and he is going to try the concoction with the borax, bleach, Dawn, etc. first and see how it works. If that doesn't work maybe I'll get him to try the Roebic or make a visit to the treatment plant.

Woody

Well the Roebic is enzymes and does clean septics, that have caked and hardened, up to 1000 gal so it certainly should losen that  small tank, even if you used the whole bottle.

Woody said:

Thanks Chet and Shayne, I'll pass it along. I talked to him last night and he is going to try the concoction with the borax, bleach, Dawn, etc. first and see how it works. If that doesn't work maybe I'll get him to try the Roebic or make a visit to the treatment plant.

Woody

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Hate to tell you this but adding bleach to the tank now will only make it worse since bleach KILLS the bacteria/enzymes that will help digest the mess.  Shayne's or Chet's recommendations are the ones to follow.  I would NEVER add bleach to my black water tank cause it does almost as much damage as formaldehyde products.

Ron, I would like to take a bit of an exception to your answer.

I believe the idea is to totally clean and sanitize the tank, i.e. start from scratch like a new tank. After that regular tank maintenance, whichever way one chooses, can be put to use.

I am personally a weekend traveller (short periods) and don't rely on any enzyme action. I clean it totally on every home trip and leave it with 1/4 tank clean water, during subsequent storage. This also keeps the sensors from drying out. My sensors are working great now and see no deterioration over the last year.

I see the enzyme point if you travel extensively over long periods.

FWIW, carson FL

carson said:

I believe the idea is to totally clean and sanitize the tank, i.e. start from scratch like a new tank. After that regular tank maintenance, whichever way one chooses, can be put to use.

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Carson

I'm confused. What is the purpose of sanitizing a sewage holding tank ??? ???  What do you gain, clean xxxx?

Carson, I think you might have missed the fact the the tank was allowed to dry out when it was full of waste and the object is to remove the accumulated waste-now like dried cement.

Woody, If your buddy adds chlorine, he'll just make matters worse. In my prior life, I used to teach courses for waste treatment plant operators. If we wanted to stop all bacterial action, we'd use chlorine. He wants to remove the dried sludge, not sterilize it and leave it in place. The anaerobic sludge or enzymes is about the only way he has a chance to break it up--unless he wants to stick a pressure washer wand down the hopper and blast it loose. When a waste water plant wants to clean a tank, they NEVER consider chlorine. except as a sanitizing agent AFTER the tank is clean.

Chet18013

Before we retired we also had MH for weekend and vacation travel.  I never found it necessary to sanitize the BWT with bleach or such.  BTW we have NEVER had unreliable sensor readings in any of the three MH.  Bleach is almost as bad as Formaldehyde products in a BWT.  Using a product like Purepower will keep you tank healthy.  My opinion based on several years experience.