What to Use to Clean Water Tanks ?

[s/v Geneve]

I recently discovered small amounts of mold floating in the top of my forward water tank after a fill-up. I have just purchased the boat recently and have not even used a full tank of water through either tank, but due to length of time that they have set up prior to my purchase I assume that they both need to be cleaned throughly.

My question would be what is the best cleaning solution and method for cleaning your water tanks?

I have a removable inspection plate at the top of both metal tanks that will easily accommodate a long brush to scrub the sides with, but is there something else that needs to be done? I will be moving on the boat soon so I want to make sure that this is done properly. Thanks in advance.

Daniel

[Cheechako]

Is it possible to use a pressure washer? That might be more effective than a brush for some areas. ...if you have baffles in the tank either is a problem. I would fill the tank completely with water, (put a good dose of bleach in). Let it sit overnight, disconnect the hose so it runs to the bilge, pressure wash/scrub etc, hose out until the water runs clean out of the tank with no chunks. Seal it all up and fill the tanks. Do you have a good water filter? If not install one. Just a good household one is fine... plastic housing about a foot long and 4" diameter..

[S&S]

Steam cleaner- usually you can rent one. Absent that, as Cheechako says, a pressure washer with some disinfectant should work almost as well.

[Fishman_Tx]

(Awright Cheech beat me to it! Sry for the repeat...)

I know I'm gonna catch hell for suggesting it....but....

If you have metal tanks, bleach. Here's what we did.
Disconnect and cap the outlets so you don't get it into the lines (we replaced all our lines cuz they were nasty). Won't hurt you but you'll taste chlorine for a while. Add bleach to the tanks, fill with water to the top(!), cap, and let sit a couple days. This kills every bit of mold in it. Drain. Use a garden hose and spray nozzle to wash the mold off the walls and baffles. Drain. Get as much of the particulates out as possible, flush thoroughly. Also, it wouldn't hurt to change the supply lines as mold can set up house in there as well. Adding at least an inline sediment filter would be a good idea also (cheap Home Depot variety).

If you have plastic tanks, you'll need to use a biocide for that purpose instead of bleach cuz plastic retains that wonderful chlorine flavor! . Same procedure as above. A food-grade sanitizer flush of the whole system wouldn't hurt either.....

My .05c worth....

[Fishman_Tx]

Sanitizer...
Marine Applications
Fresh Water Tank Sanitizer

[Charlie]

I just cleaned my tanks recently here is what I did. 1/2 cup bleach per 10 gallons of water. (Google "Cleaning RV water tanks" and this is the average concentration of bleach I found)Mix the bleach with water before adding it to your tanks. Fill tanks so that the filling process agitates the bleach. (My tanks were neat empty when I started) Run every fawcet one at a time until you smell bleach. Then let the bleach set in the tank overnight. Empty out the tank. I did this by diconnecting the hose to the tanks and letting them drain into the bilge where a stronger pump than my fresh water pump let the water out of the boat. Also helps clean the bilge. Fill the tanks again with water. Leave the fill caps open for a couple of days so any bleach can evaporate. Run the water thru the fawcets again for a few minutes each. I have no access to the tanks If I did I would scrub them with a brush or a pressure washer. On the third time of rinse/repeat the chlorine taste is gone for me but the admiral might say something different.

I was told by a water plant manager that I would be amazed about how much seditment is in a water supply. I use a household filter to fill my water tank. It has two hose adapters on the end and I trap quite a bit of stuff when I use the filter.

[Kefaa]

Presuming you are still in Florida, you have options and issues. First, "clean" is a relative term. As several have pointed out, you need to sanitize. Worse (or better), you need to do it in an environmentally safe fashion. Dumping chlorine overboard, in the concentrations required to kill a visible mold issue is going to be...problematic.

For my RV, I follow these instructions ( How to Sanitize Your RV Fresh Water System ). If you can see "stuff," you have a serious issue. You will hear people say they have drank worse and not even been sick. Good for them, and if you like to gamble - go for it. Otherwise, presume the system was contaiminated with diesel for a better idea of what you want to accomplish in regards to "clean" (see WHO example: http://www.searo.who.int/LinkFiles/L...rage_tanks.pdf)


A few things to consider, based on the fact you see colonies now:

• The incoming and outgoing hoses probably need to be replaced. You can clean them, but it is probably hours of work that will result in compromised lines at some point.
• With sanitizers "more is not better." They are toxic and high concentrations work on people too.
• If you can possibly get into the tank that is the best option. I have had limited success with pressure washers because of the angles. Has anyone found a good 90 degreed angled wand?
• Don't forget all the hoses where fresh water runs - shower, sinks, head?.
• If you have a fresh water head - have it pumped first as this is going to screw up the balance in it. Then have it pumped after.

Once it is clean and sanitized keeping it that way is the key:

• If it is not in use - empty it. If you can leave it open, even better.
• In the US water comes chlorinated from the tap. If you filter it while it goes into your tanks, you are removing the one thing that will keep "stuff" from growing.
• No harmless chemicals exist. If you do "more is better" in the maintenance steps you are going to cause health issues.
• Buy a good chlorine filter for the tap to remove the final taste.

good luck.

[Solitude]

I was able to reach into my plastic tank. Mixed the solution of bleach and water and purchased a clean, new toilet brush from IKEA for 2 bucks.

I scrubbed the tank inside top to bottom. I then pumped the solution into the water lines, to the head and galley sinks.

I let it sit that way overnight. The next day I pumped out all of the solution ( you should have seen what came out) and refilled the tank full. I used a slightly weaker solution and went sailing. I left it in during the day sail in order to allow it to slosh around. Finally I flushed the tank with fresh water several times. There was a slight chlorine smell to the water that soon went away.

My neighbor (who has the home made dock cord and chewing up my zincs!!) also tends to leave the water hose end lying in the water. I finally purchased a new dock hose to use while filling the tank.

Prevention is very important.

[Fishman_Tx]

Here's a nice NON-TOXIC sanitizer from one of my brewing sites...
Star San Sanitizer for Home Brewing

[Firehoser75]

I received the following advise from Peggy Hall, also known as the "Head Mistress" and Sue Canfield, a marine surveyor. Peggy has written a very good book on boat heads and water systems.

To correct your water quality problems, start with a stem-to-stern inspection of the potable water system. Start with the deck fills. To prevent someone from inadvertently filling your water tanks with fuel (Believe me, it happens!), the deck fill fittings should be clearly labeled “water” or have a blue plug. With a deckplate key, unscrew each deck fill plug and look at its O-ring. If the plug isn’t water-tight (because the O-ring has deteriorated or is missing) contaminants will find their way into the tank.
Moving below, inspect the water hoses and clamps at the deck fill pipes. Look too at the condition of the hose. If the hose casing (outer surface) is discolored, cracked or tacky to touch, go get a tape and measure the hose run that needs to be replaced. Next, inspect the tank vent hoses. Vent hoses may run to external vent fittings or they may terminate inside the boat. In the latter case, make sure the end of the vent hose is higher than the tank’s deck fill. Ensure too that the exterior vents or ends of the vent hoses have screens to keep insects from taking a swim in your drinking water.
If your boat’s tanks have inspection ports, remove them and look inside. Tank cleaning to remove accumulated sediment may be in order. Next, follow the water system piping from each tank to the pressure pump. There should be a strainer (typically 50 mesh) installed in-line to prevent foreign debris from entering and damaging the pump. Clean this as needed. . From the water tanks to each fixture, note the type of piping used, its diameter and condition. Depending on your boat’s age, you may find annealed copper piping, PVC (polyvinylchloride) hose, gray PB (polybutylene) or PEX (cross-lined polyethylene) tubing or a mix of materials. Of the four materials, PVC hose typically has the shortest service life. Identify piping segments that need to be replaced due to deterioration or the use of inappropriate (non FDA-approved) materials.

Sanitizing Your Water System

Always disinfect your boat’s potable water system at the start of each boating season and whenever water taste, odor or appearance becomes a concern. Before starting, ensure that the water heater is turned off at the electrical panel. Ice-makers should be turned on to allow the feed line to be disinfected. Remove any filter cartridges as well as any aerators at faucets. Flush the entire system with potable water and then drain it completely through every faucet.
Next, fill the entire system with a chlorine solution (approx. 1 ounce of common household bleach per gallon of tank capacity). Run the water from each faucet or outlet until you can smell bleach at each location. Leave the system pressurized with this bleach solution in it for at least 4 hours, but not more than 24 hours. Drain the entire system again, flush it thoroughly with potable water (fill and drain at least 2 times), and discard the first two buckets of ice generated by the ice-maker (if installed). Fill the tanks with potable water, clean the sediment filter installed to protect the pressure pump, and install new water filter/purifier cartridges as appropriate. Clean and reinstall the aerators at the faucets.
Water treatment systems (filters) can be used to remove taste and odor as well as sediment, rust, algae and other microscopic solids. Point-of-use (POU) systems treat water at a single faucet. Point-of-entry (POE) systems treat water as it’s drawn from storage tanks or enters the boat via a city water inlet. I recommend both.

Remember, algae and contaminates can thrive in the entire water system, not just the tanks. Other than aluminum tanks, which are not approved for drinking water storage, bleach in these concentrations (and durations) will not harm the tanks or plumbing.
Good luck and hope this helps,
Tom

[Kefaa]

The Head Mistress reminded me of something else --- BEFORE flushing the water to the sinks and shower - remove any end of line filters. They will clog almost instantly making water spray in all sorts of interesting and unfortunate directions.

Also, make the first run into a bucket - no sense sending the goop into the drain lines.

[s/v Geneve]

Thanks to all for the fast responses! I'm not sure if the tanks are baffled or not but I will be finding out shortly. I do have a pressure washer which I will use in combination with a brush and the bleach solution as recommended. I do have filters installed in the boat, but I will also be putting one on the marina's water line at the dock as well. I will try and change all of the freshwater lines that I can get to while I'm at it. I'll let you know how it goes.

[planetluvver]

Originally Posted by Fishman_Tx

Here's a nice NON-TOXIC sanitizer from one of my brewing sites...
Star San Sanitizer for Home Brewing

I had hoped for a recipe for a killer brew. Alcohol is a GREAT sanitizer, and much tastier than water! LOL

[Excalibur5]

Kefaa-

When I had a RV, I used this wand to rinse clean the black water tank:

Save at Pacific RV Parts - RV Parts and Supply

If you got one new, it should work well as a 90 degree wand to get the sides of the tank rinsed off well. It lets out a very high pressure stream from just a water hose.

However, depending on the location of your tank, the wand might be a bit hard to insert in the cleaning port.

[thinwater]

I like this one; very simple and I have been happy with it.
Waterguard In-Line Filter

We actually keep it on-deck in a pouch for easy use. I just screw it on the end of the hose, where ever we are cruising.

The point is to keep fine solids out.