Cleaning water tank

[Cruiser2B]

I just bought a boat with a 30 gallon water tank, it is incorporated into the hull. How would i go about cleaning the tank and lines... would running bleach through it do the trick? Should I use something else? It was used about a yr ago but not since.....Please give me some advice.

[Faster]

Google "Peggy Hall Headmistress" - She's a recognized expert in head and water systems on boats.

From another posting, attributed to her:

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.

[sailingdog]

One thing, once the tanks and lines are contaminated, the only real way to clean them is to replace the lines and mechanically scrub the tank. Bleach will help, but will not kill of all of the contamination, if the bioslime layer is thick enough.

[Cruiser2B]

Thanks, I am just curious, I will get the boat back here with bottled water, But thought about putting cleaning solution into tanks and lines to slosh around while we head up the ICW. Thanks for all the input.