By Rich

As I predicted, bottom of the aft 50 gallon tank on Rover, which is located under the aft cabin berth, was by a considerable margin the most disgusting because the tank was likely the most seldom used by her prior owners.

Editor’s note: these photos are pretty gross so viewer discretion is advised before scrolling down.

Here are some tips for avoiding this situation from recurring once you’ve cleaned your water tanks out:

1. Between cruises, empty all tanks but one and frequently turn the water in that tank over. We are going to choose the forward 49 gallon tank aboard Rover and plan to let water get no older than two weeks at the outside. If the water hasn’t been used by that time, we’ll deliberately dump the remainder and refill.
2. When re filling an empty tank, open a faucet and let the water pump run for the first 30 seconds or so of filling. This will flush the last bits of water left in the tank through the system  and down the drain so you turn over 100% of the water in the tank.
3. Empty the very last bits of water out of tanks that have been run dry if you don’t plan to refill them for a while. On the Sabre, we used a dinghy hand pump (bought new and dedicated to this purpose) and sponged out the remainder via the inspection port. For the Hylas we’ll be buying a smaller hand pump with a flexible hose that can reach the very bottom of each tank.
4. We use water treatment but only for water that will sit as long as a couple of weeks. We don’t typically bother during a cruise because the water will turn over quickly enough that treatment shouldn’t be needed.
5. Regularly inspect the tanks to be sure gunk and growth aren’t building up.
6. Do you have an on-board filter for drinking water (such as the Hylas’ Seagull filter)? If so, have you changed the filter recently? Our Sabre had a big blue carbon filter for all of the water faucets (as opposed to the Seagull for dedicated drinking water) and when I would let it go too long before changing the filter, it would get NASTY. Shockingly so, actually. So use one of these for drinking water and change the filter often. Be sure to log changes too so you know how long it’s been.
7. Use an inline water filter on the end of your hose when filling water tanks. They can be found at any marine store. Without one, all manner of debris finds its way into the tanks. Look at this shop towel from our aft 50 gallon tank: