Gray Water Tank Maintenance

[ranger58sb]

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.

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.

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.

Why do you have grey water tanks?

And if they're not necessary for some reason (legal? or...?), then why not re-plumb your sink drains directly overboard? On your current boat.

-Chris

[Dockhead]

Originally Posted by ranger42c

Why do you have grey water tanks?

And if they're not necessary for some reason (legal? or...?), then why not re-plumb your sink drains directly overboard? On your current boat.

-Chris

Several people have asked this question, so I'll answer it here for general use.

Our boat has a raised salon with the galley a step down. The galley floor is below the waterline. The galley sink is inboard and not that high above the waterline. Therefore the designer (the great Bill Dixon and his team) plumbed it to a gray water tank below the galley sole which collects the drainage from the galley sink, and aft shower and sink.

I will try to avoid this kind of arrangement on my next boat, but this is what I have now and it would not be practical to change it.

[Dockhead]

Originally Posted by 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.

I'm interested in how this works -- do you switch on the pumps manually, and do they run continuously? Or is there some kind of level switch?

I note that Whale now makes a Gulper with an electronic switch which senses water in a manifold.

I know I just posted that I can't really modify my existing setup, but perhaps I could substitute something like this. Pricey, but would plumb right in and would seem to solve the problem (and free up some space to boot).

[Dockhead]

Originally Posted by wrwakefield

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.

Thanks very much to you and to A64Pilot for this hot tip.

This might be the ticket. A brief Google excursion shows that there are various enzymatic drain cleaners/tank maintainers on the market, like Rid-X, Roebic K-67, probably many others. Anyone try any of these on a gray water tank on board?

Also, anyone know whether lye will eat up your pump membranes, level switches, etc.?

[redhead]

We've been dealing with this for a year now. Eventually will get rid of gray water tank but there's a lot of other jobs more urgent. Crusty Chief is right on the money; multiple flushes with water as hot as you can produce and then a flush with white vinegar and then I put "an ample sufficiency" (whatever I think is good) of vinegar in the tank and leave it there as a preventive for the next batch.
The smell like a dead wombat wearing old sweatsocks is gone!

[Kenomac]

Originally Posted by Dockhead

I'm interested in how this works -- do you switch on the pumps manually, and do they run continuously? Or is there some kind of level switch?

I note that Whale now makes a Gulper with an electronic switch which senses water in a manifold.

I know I just posted that I can't really modify my existing setup, but perhaps I could substitute something like this. Pricey, but would plumb right in and would seem to solve the problem (and free up some space to boot).

You can easily convert you galley sink over to this arrangement. The gulper switch is in the upper right corner of the picture. The galley sink acts as the grey water tank and drains directly to the Gulper pump, which then flows past an anti siphon, then discharges overboard just above the waterline. Simply bypass your grey water tank and you have the setup. When doing dishes, allow the sink to slowly fill up, then intermittently switch on or off the Gulper pump as needed. Always keep a sink strainer over the sink drain and empty it overboard.

[Dockhead]

Originally Posted by Kenomac

You can easily convert you galley sink over to this arrangement. The gulper switch is in the upper right corner of the picture. The galley sink acts as the grey water tank and drains directly to the Gulper pump, which then flows past an anti siphon, then discharges overboard just above the waterline. Simply bypass your grey water tank and you have the setup. When doing dishes, allow the sink to slowly fill up, then intermittently switch on or off the Gulper pump as needed. Always keep a sink strainer over the sink drain and empty it overboard.

Thanks -- interesting.

Did you convert this from a different arrangement, or was your boat built like that?

[Dockhead]

I have ordered a bottle of "enzymatic drain unblocker". It's supposed to dissolve all this carp. This type of thing is widely enough used that one would think that it is not a hoax, but we shall see. I'll report on how it works.

[Kenomac]

Originally Posted by Dockhead

Thanks -- interesting.

Did you convert this from a different arrangement, or was your boat built like that?

It's the way Oyster designed the system. Each head sink and shower empties into its own grey water tank which leads to a gulper, anti siphon then overboard just above the waterline. When showers are taken, the gulper pump runs the entire duration of the shower. Nothing stays in the tank except for the occasional hand rinsing waste.

[Dockhead]

Originally Posted by Kenomac

It's the way Oyster designed the system. Each head sink and shower empties into its own grey water tank which leads to a gulper, anti siphon then overboard just above the waterline. When showers are taken, the gulper pump runs the entire duration of the shower. Nothing stays in the tank except for the occasional hand rinsing waste.

So you have five (5) separate tanks, gulpers, through hulls?! Wow.

[Scaramanga F25]

Gray water tanks are mandatory in fresh water lakes and rivers in Canada.

[Kenomac]

Originally Posted by Dockhead

So you have five (5) separate tanks, gulpers, through hulls?! Wow.

Three gulper pumps, two grey water tanks. Galley sink, forward head and stern head. Each head has its own grey water tank and pump, the galley only has the gulper pump.

[Exile]

Dockhead -- my boat's galley sink drain set-up sounds similar to Ken's. With the sink drains situated below the waterline and no grey water holding tank, it relies on an electric pump with a simple push-button switch to drain the sinks. In my case the pump is also a macerater so any food bits that get past the strainers get chewed up & spit out, in this case straight down a thru-hull in the bottom of the hull & directly underneath the sinks & pump. Given what a PITA it would be should the pump crap out at sea I keep a spare under the sink with all the proper fittings already attached. Fwiw, this macerator-type pump is made by "Oferdorfer" & was already in place when I bought the boat.

As for grey water from the two heads, the sinks drain directly overboard via thru-hulls at the waterline, and the showers via separate Jabsco diaphram pumps via above-waterline thru-hulls at the transom (with strainers & anti-siphon loops). As others have commented, yours is the first boat I've heard of with grey water tanks. From time-to-time I hear about threatened legislation/regulation requiring such tanks, but this would likely be a nightmare to retrofit for boats like mine.

Best of luck with resolving your dilemma. It's always something!

[peghall]

Originally Posted by timbenner

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.

With the "Sea Fresh" system installed (which you have), you can use salt water most of the time...using fresh water only once a day and/or when closing up the boat to rinse it out of the system. Contrary to popular belief, salt or fresh only makes a difference in the plumbing, it makes NO difference IN the tank...there's so much bacteria in waste that the tank doesn't even notice a little more in the flush water. So as long as you rinse it out of the plumbing at least daily--and especially before the boat will sit, you won't have any more odor than you'll have using fresh water all the time.

[ASD]

I don't have gray water tanks, just black.

However, if your tanks are poly and you have access, install one of these on the top of the tank. Then go out to the pump out and rinse your tank a few times.

I installed one on my Sea Ray black tank and it worked great!

Tornado Permanent Tank Rinser with Remote Connection - Camco 40126 - Sewer Flushing - Camping World