Draining a water tank help

[Dave_E]

Hi All,

I have (2) 75 gal water tanks, somewhere between 1/4 and 1/2 full. I need to drain them (old water). Does anyone know of a sump pump set up that will work?

Dave

 

[rwidman]

1) Pump the water out with your boat's water pump. Just turn on one or more faucets.

2) Some boat water tanks have a drain. Hook a hose to it and open the valve.

3) Disconnect the water lines from the tanks and let them drain into the bilge.

 

[Larry M]

Why not use your domestic water system and just dump it in the sink? If your pump is 3 gallons per minute it won’t take very long. You’ll probably need to clean the screen on the faucet when you’re done though.

 

[Shrew]

I drain mine through a freshwater washdown spigot on the bow (foredeck) to avoid draining into a sump box. this way it drains out a scuper. No sense in running 2 pumps (one to drain the tank and one to discharge the water from a sump box).

 

[sunchaser]

I drain mine to the bilge once per year and flush it out a few times with bleach while doing so. Done it this way on several vessels i've owned over the years.

 

[Northern Spy]

I took off a threaded elbow just downstream of the isolation ball valve and put on a tee with a plug just for this purpose. Drain to the bilge in the winter or long periods of non use.

 

[RT Firefly]

Greetings,
Mr. DE. For the small volume of water involved, the suggestions thus far, depending on the geometry of your tanks, are most probably the best and most cost effective.

We carry 550 gallons (US) and I've invested in a submersible sump pump to drain the tank, when necessary.

 

[Jbear]

Dave,
Be careful with the bleach suggestion as you have stainless tanks. Read up on it before doing it as the two don't mix well.
Jeff

 

[sunchaser]

Bleach and SS are quite compatible in the strengths commonly used for water and systems treatment. But, I have heard dock talk to the contrary, old wives tale maybe. Jbear, could you point me towards a book or treatise on this. My commercial water treatment past use using Cl gas used SS equipment liberally.

 

[AusCan]

According to the Australian Stainless Steel Association, 304 stainless is ok with up to 2ppm chlorine long term. 316 stainless is good for 5 ppm.
Higher concentrations are ok for short term disinfecting.

 

[hmason]

The real problem is chlorine in aluminum tanks.

 

[DHeckrotte]

Concur with the drain to bilge folks. Bilge pump is 'way more than adequate. You'd have to wait for a coon's age to pump the water out with the water pressure pump.

 

[C lectric]

I bought an old, used, Jabsco diaphram pump that worked.

Set up a soft copper diptube , 3/8 od , which can be slid down the tank filler hose until it hits the tank bottom. The hose on mine is not truly straight so the copper has to be tweaked a bit to get it to go down. Cut the end of the copper on at least a 45o angle. Used some hose to connect the two. Setup an overboard hose from the pump.

I used garden hose couplings, male and female, to connect it all.

Mount the pump on a piece of plywood a bit bigger than the pump. Mine, while running, slid and flipped and put a scar in the gelcoat. Small but annoying.

I then leave the pump to do it's thing. At 3 gpm I can estimate how long I have to do something else. Coffee, read, fool with some thing else. The nice part about these pumps is they can run dry for a long time without being damaged.

I take my boat out with the tank ~ 1/3 to 1/2 full with the pump and diptube setup on a rough day. Get that water slopping around inside the tank with pitch and roll and run the pump and it will clean the tank.

 

[HopCar]

Won't draining the tank into the bilge sink the boat? Wait, what? Never mind.