Ok...since you asked so nicely, here are the "bare bones:"
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. 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. 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…bleach does absolutely nothing to improve the flavor of good Scotch!
1. Prepare a chlorine solution using one gallon of water and 1/4 cup (2 oz or 25 ml) Clorox or Purex household bleach (5% sodium Hypochlorite solution ). With tank empty, pour chlorine solution into tank. Use one gallon of solution for each 5 gallons of tank capacity.
(Those are the “official” directions. They work out to 1 quart/litre of bleach/50 gallons of water tank capacity , which is MUCH easier to calculate! )
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 vessel motion.
6. Drain tank again through every faucet, and flush the lines again by filing the tank 1/4-1/2 full and again flushing with potable water.
And btw, this will also remove the taste/smell of antifreeze in the fresh water.
People have expressed concern about using this method to recommission aluminum tanks. While bleach (chlorine) IS corrosive, its effects are cumulative. So the effect of an annual or semi-annual "shock treatment" that will only remain in the tank for a few hours is negligible compared to the cumulative effect of holding chlorinated city water in the tank for years.
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 (a good time to wash the boat)...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 certainly 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. You'll know because the water will be a lot colder.
This is a bit more than just the bare bones, but I'm a pushover for anyone who can turn begging into an art form. 
Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein
