Shocking water tanks after emptying for winter?

[desodave]

I empty my fresh water system before the worst of winter sets in here in BC. Temperatures here have been down to -15 deg C although water temps remain +7-8 deg C at a nearby weather buoy ... the boat stays in the water. I've been tempted to leave water in the system but am concerned about protracted power outages from a winter storm.

Is it necessary to shock the tank(s) every year when commissioning again in the Spring? I have been doing that ... using 1 1/2 cups of bleach in a full 80 USG plastic tank (inc water heater), let it sit overnight, then drain. However, it usually takes 3 fill/drain cycles to get rid of the bleach taste and requires running the water pump excessively imo to drain each time.
The new to us boat has 2 plastic tanks (100 USG total) so longer draining times and pump use. Thanks for any input.

[Jammer]

Originally Posted by desodave

Is it necessary to shock the tank(s) every year when commissioning again in the Spring? I have been doing that ... using 1 1/2 cups of bleach in a full 80 USG plastic tank (inc water heater), let it sit overnight, then drain.

That's a lot. Usually I would use like a 1/4 cup for an hour for that.



The right way to do it is to get free chlorine test strips (cheap at amazon etc) and use enough bleach to get a high enough concentration (ppm) for a long enough time to meet FDA/USDA guidelines. Water chemistry varies as does the nitrogen load in your tanks and lines so it is impossible to get the chlorine dosage right without testing. That is what I will be doing this coming spring.

[Mike OReilly]

Originally Posted by desodave

Is it necessary to shock the tank(s) every year when commissioning again in the Spring? I have been doing that ... using 1 1/2 cups of bleach in a full 80 USG plastic tank (inc water heater), let it sit overnight, then drain. However, it usually takes 3 fill/drain cycles to get rid of the bleach taste and requires running the water pump excessively imo to drain each time.
The new to us boat has 2 plastic tanks (100 USG total) so longer draining times and pump use. Thanks for any input.

I can't say if it's necessary, but we always drain and winterize our water tank and systems, and then shock it in for the Spring recommissioning. I'd have to dig into the files, but that sounds about the right concentration of bleach for a shock, which for us means leaving it in for about six hours. Our tank is stainless steel.

[peghall]

Wait until spring to do it as part of spring recommissioning. Save these directions:


Although most people think only in terms of the tank, the plumbing is actually the source of most foul water, because the molds, mildew, fungi and bacteria which cause it thrive in damp dark places, not under water. Many people—and even some boat manufacturers—believe that keeping the tanks empty reduce the problem, but an empty water tank only provides another damp dark home for those “critters.”

There are all kinds of products sold that claim to keep onboard water fresh, but all that’s really necessary is an annual or in especially warm climates, semi-annual recommissioning of the entire system—tank and plumbing. The following recommendations conform to section 10.8 in the A-1 192 code covering electrical, plumbing, and heating of recreational vehicles (which includes boats). The solution is approved and recommended by competent health officials. It may be used in a new system a used one that has not been used for a period of time, or one that may have been contaminated.

Before beginning, turn off hot water heater at the breaker; do not turn it on again until the entire recommissioning is complete.

Icemakers should be left running to allow cleaning out of the water feed line; however the first two buckets of ice—the bucket generated during recommissioning and the first bucketful afterward--should be discarded.

1. Prepare a chlorine solution using 1 quart bleach/50 gal water tank capacity

2. Complete filling of tank with fresh water. Open each faucet and drain cock until air has been released and the entire system is filled. Do not turn off the pump; it must remain on to keep the system pressurized and the solution in the lines

3. Allow to stand for at least three hours, but no longer than 24 hours.

4 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, because 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.

5. To remove excess chlorine taste or odor which might remain, prepare a solution of one quart white vinegar to five gallons water and allow this solution to agitate in tank for several days by vehicle motion.

6. Drain tank again through every faucet, and flush the lines again by fill the tank 1/4-1/2 full and again flushing with potable water.


--Peggie

[desodave]

Wow Peggy ... that's 4 times more bleach than I've been using. I took my ratio from a Yukon Gov't Public Health site and lots of people there have indoor water tanks to get them through the winter.
Do you put the vinegar solution just in the tanks? Or run it into the lines and hot water heater ( 8 USG capacity) as well before leaving it?

[bgallinger]

Following!

[CaptTom]

Do you really need to fill the tank completely? I carry over 200 gallons. I think I'd wear out the pump with all those fill and drain cycles. And emptying the tank through the faucets would take forever.

[NYSail]

Personally I use Peggie’s beach to water ratio with only 15 gallons of water. Enough to run through all lines. Then I use a sprayer (1 gallon chemical type) with the same ratio and spray down the entire interior of the tank and let that sit. Then I will do a rinse of the tank and flush out the lines……. So far this has worked perfectly. However if your tanks/lines are in bad shape I would fill to top and scrub if you have access. I did this when i first purchased my boat as I did not know the history.
Good luck
Greg

[deblen]

Leave some chlorine in your water if you are going to drink it?
You are probably filling with chlorinated water anyway.



https://www.canada.ca/en/health-cana...orination.html


Cheers/Len

[rslifkin]

My water system gets drained and antifreezed in the fall (and filters removed from their housings). In the spring, it all gets thoroughly flushed, then bleach shocked, then flushed again and a new set of filters installed.

[peghall]

Do you put the vinegar solution just in the tanks? Or run it into the lines and hot water heater ( 8 USG capacity) as well before leaving it?

Just the tank...draining it will run it through the lines and water heater.

[QUOTE]Do you really need to fill the tank completely? I carry over 200 gallons. I think I'd wear out the pump with all those fill and drain cycles. And emptying the tank through the faucets would take forever.[QUOTE]

If you don't drain the tank through every faucet, how do you expect to flush and rinse out the lines? Two fills and drains aren't likely to harm your water pump.

[QUOTE]Leave some chlorine in your water if you are going to drink it?
You are probably filling with chlorinated water anyway.[QUOTE]

If you mean, leave some of the chlorine solution in the system, that would be like leaving some dirty water in the bathtub cuz you're just gonna fill it again anyway. But if flushing the chlorine solution gets rid of chlorine taste in the water, you can skip the vinegar rinse. However, I wouldn't if you winterized using antifreeze 'cuz the vinegar removes the taste of it.

Those directions have been around for decades--I found 'em in the owners manual for a 1985 boat. You'll find 'em on the major RV sites. Whether you want to follow 'em or not is up to you.

--Peggie

[rslifkin]

I've never needed vinegar to get rid of the antifreeze taste. I always leave the lines full of antifreeze to avoid dried residue in the system. And in the spring, a few short fills and drains of the tank get any antifreeze residue out of it. After that, I just run all of the faucets for a while (enough to put a couple hundred gallons through the system) before starting the bleach shock. By the time I'm done flushing out the chlorine, the water tastes fine.

[NYSail]

I stopped using antifreeze in the water system 4 years ago...... I use my compressor and blow all the lines. I take all the fixtures off and blow till there is no mist..... then I go back and do a quick blow-out to each again to make sure I get all the water that may have pooled. Much nicer and saves money too!

Greg

[desodave]

Thanks Peggy for your clarification re the vinegar mixture.



I will continue to shock the tanks annually and have always run the bleached water through all the faucets, and then similarly flushed through them all ... inc the shower and cockpit shower. My multiple fill/drains to get rid of the excessive chlorine taste afterwards were putting too much pressure on my water pump imo ... as well as making for a very long day on the boat. I was concerned that leaving water with a heavy chlorine taste in the tanks (after the first drain) for a couple of days might imprint the taste into the plastic, so always tried to get the whole job done in a day after the initial shock. The vinegar solution solves that problem imo. I had tried a vinegar "rinse" once but used too little vinegar/ too much water and didn't let it sit at all.

I've never used anti-freeze but then I'm not facing a month or longer of freezing temps here on Vancouver island ... I just want to protect against a prolonged power outage ( and the boat is sitting in 7-8 deg C seawater ).

Thanks to everyone for your comments

[CarlF]

I've never understood the need for a so much bleach for tanks that were clean before storage. After winterizing I do two or three 1/8th tank fills and empty to flush out the antifreeze taste from the piping. Then I fill and add bleach to about 5ppm on a test strip (pools are 3ppm). This takes less than a tablespoon of bleach for 100 gallons. I run this into all the pipes. After three hours I empty and then refill and test the chlorine level again - I'll add a bit of bleach if necessary to reach 1ppm which is municipal water level. If it is 2ppm or higher I'll empty and fill again.

Perhaps this is dangerous but I've been doing it for over a decade and to my knowledge no one has gotten sick. I don't allow bottled water on my boat because the tank water is so good.