Greywater drains

[schrater]

I’ve just discovered that my galley sink drains directly out a thru-hull just below the water line. There are no Y-valves, so presumably this is how it was designed. I had always assumed it drained to my holding tank. Is this typical?

Also, I discovered my shower drains straight into the bilge and gets pumped out by the primary bilge pump. Again, common?

These don’t appear to be aftermarket mods, but make me wonder about the rules...

 

[Airstream345]

Yes, typical

 

[BruceK]

You really don`t want shower water in the bilge, usually goes to a mini sump with filters and autoswitch pump,readily available from chandlers as a complete wired unit, which you could retrofit. The other sources typically just go overboard.
Though on IGs, all grey water goes to a tank with a float switch pump and auto/manual switch.

 

[Comodave]

Some builders ran drains below the water to eliminate streaking down the side of the boat, problem is that you get barnacles growing inside the thru hulls in saltwater and they have to be cleaned out. I prefer them above the waterline and if streaking is a problem then glue a drip edge in the thru hull so the water doesn’t run down the hull but rather drips off. The shower drain absolutely should go to a sump that pumps overboard. The smell from shower water in the bilge can get really nasty. Also put something like CP in the shower drain to help keep the sump clean.

 

[schrater]

Turns out the sinks in the fwd and aft lavs also drain directly out their own thru-hulls. And the shower is draining to a sump separate from the bilge under the engine as suggested. So literally the only things draining to the holding tank are the heads themselves. Guess I can go longer between pump-outs than I originally thought!

 

[OldDan1943]

Rather than allowing the shower and head sink drain to fill up the bilge, drain them into a shower box (see West Marine) with a float switch that will pump it up above the water line and over the side. Down side, once a week clean the strainer and wipe the soap scum off the inside. Cleaning the box is a lot easier than cleaning the bilge.
The builder said, once a month. HA HA If you and/or your lady have long hair, that strainer will fill up quickly so make it once a week or be prepared to clean the bilge.

 

[rochepoint]

Here is a link to my post on another thread about shower drains.......

 

[denverd0n]

So literally the only things draining to the holding tank are the heads themselves.

Which is exactly how it should be. Sounds like your plumbing is just fine.

 

[Lou_tribal]

You have the same setup as mine, sink draining overboard, shower in bilge.
As mentioned having the shower draining in the bilge is really not ideal and I am working on installing a sump below the shower to collect water and pump it overboard so I do not get all the dirt in the bilge.

L

 

[bgillroy]

Both shower sumps and sinks should pipe overboard above WL by few inches. Same for bilge pump and AC condensates. Look into Whale pumps avoid sump boxes if U can. Lazarette hatch gutter should drain overboard as well. Yup nothing should drain to bilge.

 

[bgillroy]

Passive grey water drains below the WL are never an acceptable risk imho. Poor design.

 

[HeadMistress]

So literally the only things draining to the holding tank are the heads themselves.


Good! 'Cuz USCG regs prohibit combining toilet waste and gray water in the same tank due to the risk of e-coli from the tank finding its way into sinks--and therefore into people--via sink drains in the event of an overflow or backup.



Guess I can go longer between pump-outs than I originally thought!


Instead of guessing, install a tank level indicator. The Profile system Profile Tank Monitors is top rated and provide an accurate 1/4, 1/2, 3/4 and FULL readout. The single tank "solo" is inexpensive and easy to install because the sender goes on the outside of the tank.


--Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein

 

[HeadMistress]

Passive grey water drains below the WL are never an acceptable risk imho. Poor design.

I think you'll find that at least 90% of sailboat builders disagree...the sinks drain below waterline on all of 'em except for catamarans. They all do have seacocks.



--Peggie

 

[psneeld]

Passive grey water drains below the WL are never an acceptable risk imho. Poor design.

You could say that about most underwater through hulls.

Well done, well maintained below the waterline through hulls are usually way less dangerous than the average boat captain.

Look at the stats and causes of thru hull isdues.