Gray Water Tank Maintenance

[Dockhead]

I cleaned out one of my gray water tanks last week -- one of the absolutely most disgusting jobs on board. It was a very great challenge to keep myself from puking.

The main sediment is some white waxy substance which is either fat from cooking, or soap from bathing. Whatever it is, it absorbs food particles and develops one of the most horribly disgusting smells I have ever experienced.

I wish that there were some way to clean this out more often, and not manually -- if there were only some chemical, not environmentally destructive, which would dissolve these deposits.

Anyone have any success along these lines?

I thought about lye, but I suppose lye would wreck the Whale Gulper pump and/or the bilge pump type float switch in the system. Or would it?

Any other ideas?


General gray water tanks which mix sink drains with shower drains are a bad idea. Sinks should go straight overboard, like my last boat. Then all you have is a shower sump, and soap residue, if it's not mixed with food residue, won't be so horrible. A note for my next boat.

[a64pilot]

RV's have grey water tanks and you can buy chemicals to clean them at RV stores, I never had a problem with mine in my RV though, so I guess I'm not much help. I think "digesters" are sold for this purpose too, I believe them to be some kind of enzyme that "eats" or dissolves grease etc?
Why not eliminate your grey water tank, is it required?

I'm sure some are better than others, here is one
http://www.campingworld.com/shopping...-128-oz-/70000

I've even heard to put a bunch of ice in your grey water tank and drive around in your RV, the ice will act as an abrasive and help remove some of the caked on gunk, then you can drain it out as the ice of course quickly melts

[steve77]

I don't know anyone with gray water tanks, so all of this is news to me. I had no idea gray water could develop such an odor.

My first thought was pouring some bleach down the drain. It can't be any worse environmentally than lye, right? If you dilute it with water in the tanks, I would think it would be okay for the pump. Not sure how effective it will be on the waxy deposits, but it should help get rid of the odor.

By the way, what are your gray water tanks made of?

Cheers, and best of luck with a messy job.

Steve

[Wotname]

Originally Posted by Dockhead

I cleaned out one of my gray water tanks last week -- one of the absolutely most disgusting jobs on board. It was a very great challenge to keep myself from puking.

The main sediment is some white waxy substance which is either fat from cooking, or soap from bathing. Whatever it is, it absorbs food particles and develops one of the most horribly disgusting smells I have ever experienced.

I wish that there were some way to clean this out more often, and not manually -- if there were only some chemical, not environmentally destructive, which would dissolve these deposits.

Anyone have any success along these lines?

I thought about lye, but I suppose lye would wreck the Whale Gulper pump and/or the bilge pump type float switch in the system. Or would it?

Any other ideas?

General gray water tanks which mix sink drains with shower drains are a bad idea. Sinks should go straight overboard, like my last boat. Then all you have is a shower sump, and soap residue, if it's not mixed with food residue, won't be so horrible. A note for my next boat.

It is almost certainly fatty deposits and when mixed with lye, the two combine to make soap. Not very nice soap but a soap nevertheless. Too much lye and the mix becomes strongly alkaline. The trick is not to use too much lye.

A dedicated shower tank will still contain fat, body fats are removed with shower, that's why we use soap!

[HappyMdRSailor]

Originally Posted by Dockhead

I cleaned out one of my gray water tanks last week -- one of the absolutely most disgusting jobs on board. It was a very great challenge to keep myself from puking.

The main sediment is some white waxy substance which is either fat from cooking, or soap from bathing. Whatever it is, it absorbs food particles and develops one of the most horribly disgusting smells I have ever experienced.

I wish that there were some way to clean this out more often, and not manually -- if there were only some chemical, not environmentally destructive, which would dissolve these deposits.

Anyone have any success along these lines?

I thought about lye, but I suppose lye would wreck the Whale Gulper pump and/or the bilge pump type float switch in the system. Or would it?

Any other ideas?


General gray water tanks which mix sink drains with shower drains are a bad idea. Sinks should go straight overboard, like my last boat. Then all you have is a shower sump, and soap residue, if it's not mixed with food residue, won't be so horrible. A note for my next boat.

Boy howdy I'm waiting on the answer to this!!!
My grey tank is only for sink drains, shower sumps are a different circuit...

Our level switch to turn the pump on gave up the ghost... A little investigation as to what replacement would be best... made me slap the access plate back on faster than you can read this... I've never in my life smelled anything so NASTY... (nor ever want to again)... A very inconvenient manual switch all of the sudden becomes VERY convenient for procrastination !

Originally Posted by steve77

I don't know anyone with gray water tanks, so all of this is news to me. I had no idea gray water could develop such an odor.

My first thought was pouring some bleach down the drain. It can't be any worse environmentally than lye, right? If you dilute it with water in the tanks, I would think it would be okay for the pump. Not sure how effective it will be on the waxy deposits, but it should help get rid of the odor.

By the way, what are your gray water tanks made of?

Cheers, and best of luck with a messy job.

Steve

So continuing thoughts... since mine is only sink drains, dish soap and food are the players, not traditional fat soap and body oils...

AS DH describes, waxy sludge, so I'm fairly convinced bleach will be of little help breaking it down.... But it's sure to help cover the bacterial odors...

My tank is PE, I suspect DH's is too...

Originally Posted by Wotname

It is almost certainly fatty deposits and when mixed with lye, the two combine to make soap. Not very nice soap but a soap nevertheless. Too much lye and the mix becomes strongly alkaline. The trick is not to use too much lye.

A dedicated shower tank will still contain fat, body fats are removed with shower, that's why we use soap!

As mentioned, The majority of what's in my tank (maybe different than DH) is not body fats/oils/soap fat...

I'm thinking a diluted liquid drain cleaner might be the way to go, but worry a tad... Until I do something along these lines... I shall continue to procrastinate with the switch!

[Dockhead]

Originally Posted by Wotname

It is almost certainly fatty deposits and when mixed with lye, the two combine to make soap. Not very nice soap but a soap nevertheless. Too much lye and the mix becomes strongly alkaline. The trick is not to use too much lye.

A dedicated shower tank will still contain fat, body fats are removed with shower, that's why we use soap!

Will lye attack the pump membrane, float switch, or other bits in the system, do you think?

If not, then this is a tempting place to start.

[CrustyChief]

I had a similar problem with my 40 ft diesel pusher. That grey water tank collected from all the sinks and showers, man was that some smelly stuff! We overfilled it once and the smell was so bad we couldn't sleep. Even after draining the tank it still stunk.
Once we got home with it, I filled the tank with hot water from the big water tank from the house several times, the crud that came out was nasty. After flushing the tank over six times it seemed to solve the problem, for the most part. On the next couple of trips I poured in a half gallon of white vinegar and another gallon of hot water and let it slosh around while traveling.
My guess is we got a little bit lazy with draining the tank and it eventually started building up with solids, maybe what you saw in your tank.
Not sure how you would get enuff hot water into your tank on the boat, but it did work on the pusher.
Best of luck!

[Kenomac]

Our galley sink pumps directly overboard via gulper pump, but we still wipe grease off plates and pans prior to washing them. Just be sure to run the gulper pumps whenever you shower or wash up, then you shouldn't have the build up problem with soap and grease, and clean out the tank more often. I checked ours recently, nothing in there after three seasons... probably because we run the pumps when the shower is in use.

[timbenner]

My conclusion is the less toilets on board the better. A toilet for each stateroom and guest that doesn't know how to use it - NO Thanks!!

Solution: I just cleaned both holding tanks, re-plumbed and re-toileted both of my heads. Here's what I did: 1) Make sewer lines as short and direct as possible - I got rid of 20' of sewer hose, "Y" valves, etc. on each head. 2) Sewage goes from toilet to top of holding tank, then out the bottom to through hull. As direct as possible. The plumbing from the factory went from toilet, 10' forward to "Y" valve, then 4' up and 10' back to holding tank or overboard. 3) My tank had dried turds that were very hard to remove - now I keep fresh water in the holding tanks - always at lease 23% full.
4) Installed Raritan Marine Elegance Electric toilets - with HIGH powered flush - to get it to the tank. 5) Installed fresh water / salt water switch. Salt water makes the whole system STINK! So we use fresh water as much as possible. Easy to do with a water maker, not so easy without in blue water.

Now I never let the system get dry. Try to keep some fresh water in the holding tank and flush it with fresh water regularly.

[pcmm]

Boats don't normally have gray water tanks. that's more of an RV thing. Just remove it. where would you pump out a gray water tank anyway?? Normally Sink drains are plumbed to seacocks.

[wrwakefield]

Originally Posted by Dockhead

I cleaned out one of my gray water tanks last week -- one of the absolutely most disgusting jobs on board. It was a very great challenge to keep myself from puking.

The main sediment is some white waxy substance which is either fat from cooking, or soap from bathing. Whatever it is, it absorbs food particles and develops one of the most horribly disgusting smells I have ever experienced.

I wish that there were some way to clean this out more often, and not manually -- if there were only some chemical, not environmentally destructive, which would dissolve these deposits.

Anyone have any success along these lines?

I thought about lye, but I suppose lye would wreck the Whale Gulper pump and/or the bilge pump type float switch in the system. Or would it?

Any other ideas?


General gray water tanks which mix sink drains with shower drains are a bad idea. Sinks should go straight overboard, like my last boat. Then all you have is a shower sump, and soap residue, if it's not mixed with food residue, won't be so horrible. A note for my next boat.

Dockhead,

From my experience, the right combination of enzymes will get rid of that gunk. I have used 3 products [each for a specific purpose...] from Unique Natural Products over the years both on boats and RVs; black and grey tanks. They have formulated the required enzyme/bacteria combinations for various jobs at hand. [black and grey tanks, shower sumps, bilge, etc.]

All products I have used work as advertised, have no odor or chemicals to harm any animals or materials, and are pretty cost effective when used as directed.

Marine Digestit works great on black and grey tanks. I always have this onboard.

RV Digestit works well in our RV tanks (black and grey) as an ongoing preventative maintenance. Treat your sump with this routinely and you won't get the goo build-up and associated odors...

Either of the above make great bilge cleaners as well as diluted in a spray bottle for spot use. [e.g., Great for temporarily deodorizing blackwater hoses that have reached their end-of-life...]

They also have an enzyme based drain opener that works extremely well.

In the US I buy these products from Amazon- often with free shipping.

Here is an article about these products by The Boat Galley as an additional reference.

If you want to give them a try and can't source them locally let me know and I'll try to help. [Since these products are water based I don't think there are any shipping restrictions.]

Cheers!

Bill

PS: I'm not an environmentalist; I will use anything that does the job. These products just work.

[Juho]

I would probably try dishwasher detergent. Letting that stuff influence the target for a while has solved some nasty problems for me. A short stormy trip out to the sea would make the treatment more efficient.

[Dave22q]

pcmm seems to have it exactly right. there are no environmental regulations on grey water. after all its just soap, fresh water and some food particles from the galley sink. these should pipe overboard. you need to replumb your lines. boats are not RV's so individual trailer park rules do not apply.

[leftbrainstuff]

If you combine the galley sink with shower run off you will create a very effective goop.

This approach is typical in RVs but not on boats. Typically your sinks will drain overboard.

Rarely do we pour fat or grease down our galley sink. We catch all particulates with a strainer. We use a good biodegradable detergent.

Our shower runoff is strained to catch all hair and scum.

We also clean our gray water sump with orange oil and hot water regularly. Once a year I remove the grey water sump and clean it.

Sent from my SM-N900T using Cruisers Sailing Forum mobile app

[canman]

Wow things can get complicated. Threw out the head and tanks and hoses. Composting air head now. Sinks drain directly thru hulls and shower has a great on off pump switch in there. Can let the shower pump run as we shower or simply turn it on to drain the shower floor when done. It goes overboard just above the waterline. Never a problem or smell. No sump!