Replace water tank or disinfect it?

[omgitsgela]

So I just acquired a 1970's catalina 25 from a friend in great condition. (the boat, not the friend.) He told me that the water tank has an awful taste to it, and he NEVER drank out of it.

I'm wondering, do I dare try and drink out of a 30 year old plastic tank, should I treat it somehow, or should I scrap it and build a new water system with cheap stuff I can find?

The plastic for the tank appears to be in rigid enough condition. Doesn't appear to really have deteriorated at all from the exterior looks...

[onestepcsy37]

in a catalina 25 the fresh water system is simple and cheap enough to just replace the whole thing. there are water tanks, hose, clamps, and manual pumps widely available - try defender -

www.defender.com

or, for just daysailing or weekending, buy a few gallon jugs at the supermarket and forget the onboard system.

[SailFastTri]

I use my boat's fresh water for washing dishes and people, and for brushing teeth -- but we use jugs of spring water for cooking and drinking. New tank or old; I don't like the idea of drinking stagnant water that's been in a dark tank within the bilge of a boat that's been baking in the sun. The following was copied from an old online post by Peggie Hall and might include some of my own edits (credit to her). I "shock" my tank like this at the start of each season and do not have bad odors. We could probably drink it and cook with it safely, but prefer the spring water:

FRESH WATER MAINTENANCE
Fresh water system problems--foul odor or taste--are typically caused by allowing water to stagnate in the tank and especially the lines, creating the ideal environment for molds, fungi and bacteria that thrive in damp dark places. Here's the recommended method for recommissioning fresh water systems; this should be done at least annually:
　
　
Fill the water tank with a solution of 1 cup (8 oz) of household bleach per 10 gallon tank capacity. Turn on every faucet on the boat (including a deck wash if you have one), and allow the water to run until what's coming out smells strongly of bleach. Turn off the faucets, but leave the system pressurized so the solution remains in the lines.
　
　
Let stand overnight--at least 8 hours--but NO LONGER THAN 24 hours. Drain through every faucet on the boat (and if you haven't done this in a while, it's a good idea to remove any diffusion screens from the faucets, 'cuz what's likely to come out will clog them). Fill the tank again with fresh water only, drain again through every faucet on the boat, repeating till the water runs clean and smells and tastes clean.
　
　
Remember: cleaning out the tank addresses only the least of the problem...most of the problem occurs in the lines, so it's very important to leave the system pressurized while the bleach solution is in the tank to keep the solution in the lines too.
　
　
People have expressed concern about using this method to recommission aluminum tanks. While bleach (chlorine) IS corrosive, the effect of an annual or semi-annual "shock treatment" is negligible compared to the cumulative effect of holding chlorinated city water in the tank for years. Nevertheless, it's a good idea to mix the total amount of bleach in a few gallons of water before putting it into either a stainless or aluminum tank.
　
　
People have also expressed concern about the potential damage to rubber and neoprene water pump parts. Again-the cumulative effect of carrying chlorinated water is more damaging than the occasional "shock treatment." Occasionally, a water pump has been known to fail immediately after recommissioning, but it's always been an older pump in which the diaphragm and/or valve were already "on their last legs" and would have failed soon anyway. Far better to "push it over the edge" during spring recommissioning than have it fail a month later at sea with no replacement parts aboard.
　
　
To keep the water system cleaner longer, use your fresh water...keep water flowing through system. The molds, fungi, and bacteria only start to grow in hoses that aren't being used. Before filling the tank each time, always let the dock water run for at least 15 minutes first...the same critters that like the lines on your boat LOVE the dock supply line and your hose that sit in the warm sun, and you don't want to transfer water that's been sitting in the dock supply line to your boat's system. So let the water run long enough to flush out all the water that's been standing in them so that what goes into your boat is coming straight from the water main.
　
　
Finally, while the molds, fungi and bacteria in onboard water systems here in the US may not be pleasant, we're dealing only with aesthetics...water purity isn't an issue here--or in most developed nations...the water supply has already been purified (unless you're using well-water). However, when cruising out of the country, it's a good idea to know what you're putting in your tanks...and if you're in any doubt, boil all water that's to be drunk or used to wash dishes, and/or treat each tankful to purify. It's even more important in these areas to let the water run before putting it in the tank-wash the boat, whatever it takes...'cuz any harmful bacteria will REALLY proliferate in water hoses left sitting on the dock.
　

[dohenyboy]

Replace the tank or cut an access hole to clean it. A pressure washer would be good.

All that is above is great. Change all hoses, etc and shock clean system.
I bought the biggest whole house water filter at Home Depot i could find. All water goes through it before going in the tank. Use only white hoses for filling the tank.
Galley water goes through very fine filter then UV purification.
What do you think they do to the tap water which is safe to drink? Or well water?
No magic here
Water tastes great. Nice ice too

[boatman61]

I keep my tanks/water clean by putting a capful of bleach in with every fill-up... follow the tank cleaning directions above... then as I said.. a capful/tank will keep things fresh

[DefinitelyMe]

I do the same as boatman - a capful of bleach every time i fill the tanks (about 20 gallons each). Mine are home-made plywood and epoxy. I don't drink the water but it's good for everything else. No growth and no hint of chlorine smell or taste (i still use it for waching food and brushing teeth etc.). Might as well try it before shelling out for brand new tanks!

[sailorboy1]

I would definitely try to clean the tank and system first. Even if you replace the tank you still are going to have to do the disinfect for the lines etc.

I maintain a free chlorine level in my tanks that I test for (you can get kit kits at most hardware stores). While I can not smell the chlorine I can taste it which why I have a drinking water filter at the sink for water I plan on drinking.

[Mystic38]

+1

On a newly owned boat its best to avoid those expenses that you can avoid..

I would drain the tank, check for inspection ports and clean inside of tank. Refill adding at least a cup or two of bleach...ie way way more than that recommended for safe drinking.. run the faucets until you can detect bleach smell then leave at least overnight.

Drain and refill with 100% water & repeat until water runs clear and smell free. leave overnight and test again.. if still bad , repeat anoher heavy bleach dose.

note!!..check for a water filter, if you have one, buy several. bacteria (or antifreeze) will sit there for months contaminating the water so replace after a bleach cleaning cycle.

With a clean system, there is no reason why a boats water tanks cannot be made drinkable... if you are a casual/weekend cruiser then mebbe you don't care.. but I only carry additional drinking water for emergency backup and focus on a clean tank/system

good luck

Originally Posted by Don L

I would definitely try to clean the tank and system first. Even if you replace the tank you still are going to have to do the disinfect for the lines etc.

I maintain a free chlorine level in my tanks that I test for (you can get kit kits at most hardware stores). While I can not smell the chlorine I can taste it which why I have a drinking water filter at the sink for water I plan on drinking.

[MarkJ]

I would empty the tank and put two gallons on bleach in then go out sailing and buck the boat about. While sailing run the taps and get the bleach into all the lines.

Empty

Return home

Fill and refill two or three times with fresh.

If that doesn't fix it buy a small boy and shove him into the inspection hole.

[omgitsgela]

It would have to be a very small boy, considering the inspection hole is only 1.5 inches wide. It's a 16 gallon tank...

Will chlorine damage the plastic in such high concentrations?

There is no water filter that I could find when tracing the plumbing. It's a 1/2" plastic hose going from the tank to a manually actuated pump faucet. I don't mind filling the tank with lots of bleach, but I would have to pump it all out manually, or find a sacrificial water pump or something.

[sailorboy1]

the chlorine will not damage the plastic tanks

you have to pump the bleach though all the piping and allow to sit a while

if you use that much bleach, plan on flushing MUCH more that 2-3 times.

[DeborahLee]

I follow up the bleach flush with a vinegar flush. Same amount and let stand about 4hrs min. We had a real bad odor problem and now do this once a year as part of commissioning.

[SailFastTri]

Originally Posted by MarkJ

I would empty the tank and put two gallons on bleach in then go out sailing and buck the boat about. While sailing run the taps and get the bleach into all the lines.

Empty

Return home

Fill and refill two or three times with fresh.

If that doesn't fix it buy a small boy and shove him into the inspection hole.

That's bad advice. You don't need that much. Bleach is highly corrosive.

[MarkJ]

Originally Posted by SailFastTri

That's bad advice. You don't need that much. Bleach is highly corrosive.

Try it in a plastic cup over night first then.

BTW, when you have finished flushing out the bleach with fresh water then leave the water tank filler open for a few hours to allow any other chlorine to evaporate off. It shouldnt take as much as Don sugests.

Remember people with fish tanks use chlorinated town water suplies in their fish tanks... just let the water stand for 4 hours to let the chlorine bleed off.

[omgitsgela]

We don't have very much chlorine at all in our town water supply. Boston has some of the best water in the country, thanks to the Quabbin.

I'm more concerned about manually draining a gigantic tank out of a manually actuated faucet and how much wear it will put on the mechanism. Maybe I'll have to employ that small boy to operate the pump faucet instead