Filtering fresh water at fill

meuritt · May 30, 2009

We have excellent water here, but I still filter going into the tanks. I found a filter that screws onto the hose, claims to kill a large % of organisms, but my intent was mostly keeping out sand. Not introducing anything that will grow in the tanks just seems like a good idea. I have no idea if the exercise has any merit at all.

Then I filter what we drink from those same tanks. Water just sitting in tanks has little appeal to me.

sailingdog · May 30, 2009

If the water is that bad, you're filling from the wrong source. Potable water shouldn't have algae or other critters in it. In fact, the biggest source of potable water contamination is probably the vent line. Putting a filter in the vent line will do far more to keep the tank clean than filtering the incoming water. Also, using the water regularly is a big help to helping keep the gunk down... the stuff usually only grows in highly stagnant water.

Peggie Hall HeadMistress · May 30, 2009

Not a good idea

Filters remove the chlorine etc used to purify municiple water...so filtering it going into the tank would actually encourage "critter" growth in it. But you do want to flush out water that's been sitting in the dock supply line and your hose...so let the water run for at least 5 minutes before filling the tank.

Recommissioning the fresh water system annually according to directions I've posted here many times as a part of spring recommissioning will keep your water smelling and tasting as good as any that comes out of faucets on land. If you need to improve on that, add a filter to the faucet.

Ken Honeycutt · May 30, 2009

Dave,

I use one of these http://www.generalecology.com/category/marine-rv_filters. Not so much to keep critters and algae out but mostly to filter out sediment etc. that seems to be in the Chicago water system. I also add a couple of teaspoons of Chlorox to the tank.

catsailor · May 30, 2009

I've been happy using one of the Shurflo hose filters while filling.

jibes138 said:
Peggy,
I have your book, great book by the way, and always use your system for commissioning each spring as recommended. As a result I've never had a problem with my fresh water. Last weekend I was goofing around on the docks fixing my dinghy and my wife said "how comes there's stuff in the water." She was using the hose to fill a container for something. I filled an empty 1 gallon jug and sure enough there was what looked like algea in the water from the dock. Now the pump was opened so some work was being done to the system (it is a well) so I'm not sure what was being fixed or why, but this prompted my original post that it seems to make sense to keep particulate matter out of the tanks. Your comment about the chlorine makes sense and I hadn't thought about that. Thanks for the response.
Dave

The only other filtration I have is a simple strainer on the water pressure pump.

I worked for US Filter for 10 years and am familiar with many approaches. I don't disagree with anything Peggy said, either. The potential for chlorine removal has always concerned me. But simple is good, and many sailors have been happy with this simple approach. My suspicion, unconfirmed on my boat but observed in practice in industrial systems, is that the carbons ability to remove chlorine does not actually last very long and that it only serves as a particle and taste filter through most of its life. The thing to remember about carbon is that it does not get "used up" in an obvious manner. It first absorbs the water, then things like chlorine, but in the end has its best afinity for odor and taste producing substances, as they are bound most tightly.

Replace annually or as needed. No, I no longer work for any filter manufacturer.

Peggie Hall HeadMistress · May 30, 2009

Hey Dave...

The stuff in the water in jug wasn't algae (algae needs light), but was prob'ly mold and fungi that thrive in hoses, especially hoses sitting in the warm sunshine...and prob'ly were in the dock supply line or your own hose.

Which is why it's always a good idea to let the water run long enough to clear out all the water that's been sitting in 'em before you fill your tank. You can usually tell when the water starts coming from the main...it's a lot cooler than the water that was sitting in the lines.

Chuckbear · May 30, 2009

On our current boat and our previous one we use a charcoal water filter attached to a "Stainless" water softening system, see the picture here http://tinyurl.com/kl2ctx and the post here http://tinyurl.com/krxe7g, and the difference in the water on board has been incredible. We first used this in Houston where the water was so bad we could not wash the boat or it looked worse afterwards. We have used this filtering system every time the tanks are filled and after using it for almost 3 years now would not go any other way. As Peggy stated we always flush the hose before filling the tanks or attaching it to our filters. Chuck

Patrick S/V Shangra-La · May 30, 2009

Like Peggy recommends, I always let the water run to "clear the pipes". I only put enough water on board for about 2 weeks, then drain what ever is left in the tank before refilling. It can be a pain some times, but I am able to drink what I have in the tanks, and have had no problems from it. No I don't filter the water, either going in, or coming out.

Tom Spohn · May 30, 2009

I am fortunate that the water in my home marina is pretty good, but some of the stuff we encounter when cruising is awful ! So I pre-filter this water and have had excellent results. Filters purchased at the RV store are way cheaper than the marine filters.
http://www.campingworld.com/shopping/item/tastepure-kdf-carbon-water-filter/18478

tommays · May 30, 2009

Well

I take care of a BIG US Filter DI water system and will have to disagree about filtering

Long island has water as clean as it gets, we use 5 micron string filters as the systems first rough filter BEFORE it hits the carbon and the amount of iron and other stuff they pickup from water with a TDS (total dissolved solids ) of less than 80 is a real eye opener

catsailor · May 30, 2009

I always hose off a part of the deck first for this reason.

Peggie Hall-HeadMistress said:
The stuff in the water in jug wasn't algae (algae needs light), but was prob'ly mold and fungi that thrive in hoses, especially hoses sitting in the warm sunshine...and prob'ly were in the dock supply line or your own hose.

Which is why it's always a good idea to let the water run long enough to clear out all the water that's been sitting in 'em before you fill your tank. You can usually tell when the water starts coming from the main...it's a lot cooler than the water that was sitting in the lines.

The anchor, the tramp - something. It has become a habit, but a good habit. We are on well water and I am at the end of the pier, with some un-used work boats (I need a wide slip). The water in the line gets stagnant.

RichH · May 30, 2009

If you live in an area where the municipal water supply is from 'surface' water and isnt specifically filtered by the municipal supply to 1.2µM (at 99.9% efficiency) THEN you NEED filters to prevent either cryptosporidium and/or giardia lamdlia from entering your tankage. Both of these species are totally chlorine resistant and can yield 'awful' health consequences. In the USA and Canada, the Great Lakes, many of the Gulf states, many of the states of the Miss. Valley are most prone to these infections. FILTRATION either by 1.2µM FDA/NSF rated 1,2µM (absolute) filters or better is the primary means to prevent such from entering a system. Many of the large cities in the affected areas have already spent zillions of $US for direct filtration, etc. to prevent these from entering the water supply; but, many places are still unprotected.

Filter @ 1,2µM (absolute/100% ... or NSF/FDA 'rated' for zoocysts removal) the water BEFORE you charge your tank; keep your tank internals to the same cleanliness level that you keep your dishes and cookware, .... put a 'filter' on the VENT line - prevents aspiration of spores, etc. when you draw down the tank. If the water needs odor, etc. removal use a carbon filter in addition to the 1,2µM filter - on the fill line.
Sanitize routinely and keep enough chlorine in the tank so that you can 'just barely' perceive the chlorine odor. Simple hygiene.

Peggie Hall HeadMistress · May 30, 2009

If you're filling with well water...

You prob'ly should add a bit of chlorine to each fill. Give your local water department a call to find out how much.

bob112233 · Jun 1, 2009

Try Walmart KDF water filter.

I'm about to replace the exiting filetr in my boat water system to this model. Looks good. better than just carbon.

Filtering fresh water at fill

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bob112233