I know this is a suject that's been discussed many times already, but I thought I would share a method I recently used to sanitize my fresh water tank.
I know that a lot of folks only use their fresh water supply for showering, washing dishes and maybe cooking when the water is going to be boiled. Bottled water seems to be the popular choice for drinking. I'm ok with bottled water for drinking, but most of the time camping, water is not usually the beverage of choice by our group.
On our last trip though, I wanted to have 90 gallons of pure, safe water, so I decided to sanitize the fresh water tank, using a quat based sanitizer. Quat sanitizers are very commonly used in the food service industry and are making their way into day care as well, because of the improved safety and longer shelf life over bleach. I know this, because it's one of the products I sell for a living. What I used was a concentrated sanitizer that dilutes at 512 to 1. It's designed to be used in a dispenser that blends the solution and water together at the proper dilution ratio, by use of metering tips. Quat tablets or liquid sanitizer for commercial kitchen sinks will work as well, as long as you can determine the dilution ratio. Knowing that my water tank holds 90 gallons, or 11520 ounces, I knew that the proper amount of quat would be 22.5 ounces for a full tank. 11,520 divided by 512. Since I only wanted to fill the tank with a sanitizing solution 3/4 of the way, I multiplied 22.5 by .75 to get 16.75. I poured 16 ounces of quat into a garden hose with a funnel, then attached the hose to the fill connector and filled the tank 3/4 full. Estimated of course, by the dummy lights. This quat sanitizer has a 10 minute dwell time to kill everything on it's efficacy chart. I ran it through all faucets, including the filter for the kitchen sink. Then drove around my neighborhood for 20 minutes or so. I drained the tank, filled it again to flush out the pink solution, ran the faucets again, then did the final fill with a filter, for the water we would use for our camping trip. (no hook ups) I taste tested the water afterwards and it tasted as water should, tasteless. The dog drank the water all weekend, with no problems and we cooked with it several times and drank a little of it. No one got montazuma's revenge from the water, included our cute little shelty, Colby.
Just thought I'd share. Cheers!