Why have a gray water tank?

haukebo · #1 (**permalink**) 11-09-2006

I just inspected an otherwise nice yacht and was confused that it had (separate from a black water holding tank) a fairly large grey water tank. Why would one want to hold onto gray water as opposed to pumping it overboard? My understanding is that even in areas designated "no discharge zones" they are only prohibiting sewage from going overboard and there is little harm to the environment from my dish water. Any thoughts anyone?

Faster · #2 (**permalink**) 11-09-2006

There is growing pressure to restrict grey water discharge, esp. in small, confined but heavily used coves and bays.

Dishwater does contain detergents and cooking oils/greases that could be detrimental to marine life.

There is also pressure to use "greener" soaps for deck cleaning and hull washing.

As usual, it's a combination of political/eco pressures vs. 'real" effects of such discharges when the volumes involved are fully taken into account.

In Canada right now there is word of a new law that would require ALL vessels, regardless of use and size, to go at least 3 miles offshore before discharging - and by offshore they don't mean 3 miles from the nearest beach, they mean 3 miles off shore - ie - off the extreme west coast. For most of us inside cruisers this means a 100 mile trip around to the outside to empty our holding tanks. Like that's going to happen......

Meanwhile the city of Victoria continues to dump mega cubic meters of untreated waste directly into the sea.

It's very frustrating when common sense plays no part in these knee jerk regulations.

Sorry for getting carried away there....

TrueBlue · #3 (**permalink**) 11-09-2006

Many areas prohibit even grey water discharge, such as in Lake George, NY. I have never encountered this arrangement, but assume that since boats equipped with a grey water tank can hold onto the water until reaching permitted grey discharge areas, the smells from a separate grey water tank are tolerated by the crew a bit longer than raw sewage.

TrueBlue · #4 (**permalink**) 11-09-2006

RI only prohibits sewage discharge - treated or untreated. Grey water is still allowed to be discharged in all boating areas . . . at least up to yesterday, when we drained the galley sink in the marina after our final season clean up.

The grey tank holds water 'till reaching grey discharge areas, the black water tank until the next pump-out, beyond the 3 mile limit, or whichever comes first.

TrueBlue · #5 (**permalink**) 11-09-2006

Looks like he decided to delete his post . . . ;-)

sailortjk1 · #6 (**permalink**) 11-09-2006

Different parts of the world have different policies.
The original poster does not say where he is from.

I know that in some very prestine areas of the Great Lakes that even discharging Gray Water is prohibited.

Isle Royal National Park in Lake Superior is the one that comes to mind.

My boat has to be inspected each year to insure that the holding tank (Black Water) can not discharge overboard. If we are not compliant, we do not receive our harbor permit.

Cruisingdad · #7 (**permalink**) 11-09-2006

Well, you know what fellow sailors, the day will come when you have to have a gray water tank just like a camping trailer. Why? Because all the dead fish that are popping up in the bay and oceans are the result of cruising boats. All the mercury is the fault of cruising boats. All the bleached coral... yep, cruising sailboats. SO, once you can cut all of that off, the oceans of the world will be clean and beautiful... or at least another politician will get re-elected. Gotta love the politicians.

- CD

PS Now that I have my gray water tank installed, all I need to do is find a place to set the hook that is upwind from the billions of gallons of raw seweage the city is dumping in beside me.

svindigo · #8 (**permalink**) 11-09-2006

As far as the boat goes it does reduce the number of thru hulls you need. Our 50' ketch has 6 below WL penetrations (Intake and discharge for each head (2), raw water intake for engine and one that is not used but used to be for a reefer. Galley and head sinks and the aft shower drain to a grey water sump and that is discharged above the WL. FWIW I dove on a neighbor's Hylas 46 and counted 14 hull penetrations below WL. That's a lot of hose clamps!