Water filtration for FW tank ?

Ron20324 · Jan 30, 2016

I have a 40-gallon tank also. During the season, I only fill it as much as I think I will use fairly soon. At the dock, I use it freely, wasting it you might say, so as to empty the tank frequently. For a weekend trip, by the time Saturday rolls around I've pumped ALL the water out of the tank then refill from the dock hose. In 10 years, never had a problem drinking it. I don't think you'd EVER want to drink water out of the bay- not with Baltmire knowingly pump millions of gallons of sewage into the waterways. Is your tank aluminum?

Maybe drop in the liquid or a couple of the tablets to putrify water when you fill the tank. I use to use them at half the suggested dosage. Like fuel with ethanol, it's best to keep the water flowing to reduce potential problems.

Skipper · Jan 30, 2016

Purification might be as easy as just staying clean. Questionable water sources may require more.
Like Ron, I never fill my forward tank. Only the tank above the keel. Unless going cruising. We run through it (25g) about every 2 months, using the boat every weekend.
I scrubbed the tanks clean 5 years ago, and since have put just a tiny bit of bleach in at fill up. Maybe a teaspoon. Also replaced HW heater, which had been contributing junk.
However, I found that the head sink on the cold side was still smelly after sitting. So replaced the hose all the way back. Hot side is copper, doesn't have a problem. Might want to check your hoses.
Boat is 32 years old with original built in fiberglass tanks. Water is fresh and nice. Climates include Chrsapeake Bay and SoCal, same boat.

druid · Jan 30, 2016

What material is the tank made of? I found plastic tanks make the water taste "plasticy" no matter what you do. The fibreglass tanks in Wind Drift seem to be able to hold water for months without imparting any taste.

druid

woodster · Jan 30, 2016

Get Peggy Halls book and read what she recommends for you water system and if you do it you will be a happy camper for sure

Stu Jackson · Jan 30, 2016

Fresh Water System Recommissioning 101 http://c34.org/bbs/index.php/topic,5836.0.html

centerline · Jan 30, 2016

we have a 65gal water tank and it will sometimes remain in the tank several months before needing refilled..... and I DONT clean the tank and never have.... I did give the water system a shock treatment of bleach when we bought it, just to insure there was nothing living in there.

the water than goes into the tank must be clean and free of contaminates if you want to maintain a clean system with very little maintenance and worry....

its my opinion that you dont need a secondary filtration system on the boat, as that is just another piece in the system that needs maintenance and at the very least, isnt solving the problem...its only treating a symptom of the problem.

but a good filtration system that you can hook between the dock water spigot and the tank when refilling will filter out the contaminates before it gets to the tank... then a proper amount of bleach added to the tank for the volume of water will kill any remaining bacteria that passed thru the filter or is still living in the tank.....

I would highly recommend you add a quadruple dose of bleach to the system, poured in to the water stream while filling, then turn on all the faucets and let them run five minutes so the bleach can run thru all the lines.... make sure there is enough bleach in the system so that you can smell it in the water as it exits the faucets.... and run the hot water faucets until all the water is displaced in the hot water tank.....

then let it set for 24 hours or so, and then open all the faucets again and displace the water again.... after 2 days you can drain/pump the system and refill with filtered water from the dock spigot, add a tablespoon of bleach and be worry free..... until someone introduces more contaminates into the system by adding unfiltered water or allows it to eventually grow by not giving it a treatment after filling.

this solves the problem of having live contaminates in the system, rather than treating the symptom by filtering out the contaminates that are already living in the system whenever you want to draw from it...

centerline · Jan 30, 2016

deltaten said:
thanks guys...... but does anyone use ceramic/charcoal filters in potable line?
centerline.... that's pretty much what I do at every fill 'cept no pressure filter. real good local water from well at house..let hose run quite some time bbefore sticking in tank. usually fill potable bottles from same faucette every couple/3 days for coffee..... just fine!

you may have some deteriorating lines that is causing problems and should be replaced....

thinwater · Jan 30, 2016

Standard Chesapeake well water problems. I'm over in Deale, MD, am on well water, and know your issues. Did a series for Practical Sailor to address this.

The water is getting "skunky" because it is high in sulfate and this is converting to sulfide. It has nothing to do with the tank material. Just clean the tank. Your home well water is "good," but I'm betting it is still at the root of the problem (the reaction takes time).
Sulfide is prevented by adding an oxidizing agent (bleach). Either tablets or plain household bleach is fine. Get some test tapes (any pool or pet store). Your goal is ~ 1-2 ppm residual after a few hours. You seem to have the basics, but test to be sure. Your dose may be too low; chlorine demand depends on the water and any standard advise can be wrong. Test.
Carbon block filter, NSF 53 certified. This will remove all of the chlorine and cysts, and will help with taste. Filters Fast will have everything you need. Use 2x10 filters and the pressure drop will be low. About $35 for everything.
The primary way bad hoses contribute (and why copper is good--copper kills the bugs) is by harboring bacteria that convert sulfate to sulfide. The bleach dissipates much faster in the hoses than in the tank.
Do filter the feed water; dirt = food for bugs and a place to hide from the bleach. There is no substitute for scrubbing the tank annually.

This is more a aesthetic issue than safety issue.

Terry Cox · Jan 30, 2016

Other than when we took possession in 2002, I have yet to recommission our two water tanks; 85/65 gallons. During the cruising season I make it a point of alternating tanks and even to this day our water tastes as if it came right out of the city water tap. Erring on the side of clean, I use a PUR brand kitchen faucet spout mount filter for drinking. All other water use, such as for cooking, coffee, cleaning, washing, etc., I use straight from the tap. Our water supply comes from the Sultan watershed reservoir and has a reputation for purity.

Stu Jackson · Jan 30, 2016

I also do the same. After 27 years (16 of ours) we replaced the hoses. Don't use any filters either. We use the boat a lot, plastic tanks. I use one until it runs out (good telltale for a refill, there) and switch over. 43 & 28 gallons, plus the 6 in the heater.

thinwater · Jan 30, 2016

As I said, this is a well-known local water issue. Even within the region, it depends on where you fill (well vs. city water, which comes from reservoirs).

Gunni · Jan 30, 2016

This is basic water tank storage chemistry. You need to get your freshly filled tank up to 10mg/L Chlorine for 24 hours to kill any bacteria, or oxidize any iron sulfides. For a 40 gallon tank that represents a 1.25 oz. of 5% unscented bleach (about a shot glass). You can also do a 6 hour shock, which would be about 5 oz of 5% bleach in a 40 gallon tank. More is not better, and I see boaters dumping bleach in their tanks at a rate that will damage tanks, fittings, pumps, water heaters, valves and fixtures. Chlorine is a potent oxidizer and you want it to do it's job and dissipate. As Thinwater says, keep it at 1-2% (muni water) and you will have no problems. If you want all the chlorine out before you drink it an inexpensive big-box carbon filter will take care of that.

Here is a link to a state Health department web page with more info. The "Shock Chlorination Calculation Tool" spreadsheet allows you to determine the chlorine chemistry you need for your tank volume. Boat water tanks are vented and weakly sealed, they need to be treated with every addition of potable water.

This is a great reason to have two water tanks. You empty each one individually, fill and treat per the exact volume of water you are adding, while running on your other water tank. The treated tank is kept closed, and no further water is added until it is depleted. For this reason, every boat should have two water tanks.

thinwater · Jan 30, 2016

^^ ppm chlorine residual, not %. You knew that

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heritage · Jan 30, 2016

We have used Aquasana countertop water filters for several years in the boat and cabin. http://www.aquasana.com/product_detail.php?product_id=11 Good company support. The down side is that the water comes out of the tap slowly. Maybe 10 seconds to fill a glass. You do need to secure the unit so it doesn't slide around. Another option is to mount under the counter if you have room.

Gunni · Feb 1, 2016

thinwater said:
^^ ppm chlorine residual, not %. You knew that .

Yes thanks, ppm or mg/liter - same concentration.

Justin_NSA · Feb 1, 2016

Practical Sailor had a good write-up on the subject if you have access to it. We start with using a hose filter on a hose used solely for potable water. I would still like to do something on the tap side. Under the sink perhaps.
Has anyone cut a hole in a plastic tank and added an access panel for cleanout?

Deleted member 117556 · Feb 1, 2016

I have 55 gallons of fresh water on board and add 1 oz of bleach each time I fill the tank. Odors disappeared like magic. No need to over-think this.
bob

Water filtration for FW tank ?

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Deleted member 117556