2 things:
If this is a used boat:
You never know if it is clean or not unless you take it out and look.
Empty a gallon jug of Clorox bleach into the
holding tank, let it sit at least 15 minutes, then fill almost all the way with water. If you can, though I know it sounds silly, try to jostle the boat, thus sloshing the
holding tank contents. Empty the tank. Before the tank is totally run empty, pour another jug of Clorox into the tank, (this pulls the bleach into the
lines) let it sit again,for about 10 minutes, and almost fill with water again, and again try to jostle. After this fill with potable water and then run it through (don''t taste it). Then, once more, fill with potable water and now see how it is. If it''s still bad to you, fill (without the bleach) and try again. Test it with a common test tab from a boating or camping store. If it is still unbearable after these 4 flushes, you need to replace the tank and
lines because the bacteria has become set in the
lines. Even though you think the tank is clean, it is not necessarily so.
If this is a new boat:
If this is a brand new tank and you think the water tastes funny, it may be because not enough fresh water has been run through it. Does it taste like you''re drinking out of a new doll at Christmas? Fill the tank and empty it until it tastes okay to you. This could take from 5 to 10 times, believe me. Quite often new boats are sent out with tanks that have had antifreeze put in to protect the tank and the seals. Don''t let this be a feature of your new boat that you can''t use. (I used to deliver new sailboats and we had to use this water, at least for cooking, so it eventually gets to the point where you can stand it, and just gets better from there.)
If this is a new boat, and the water tastes a little funny, please try flushing quite a few times (like I said, even ten times is not too little). Sometimes the dealer/seller fails to mention little facts like this.
Best of luck, and please, please, don''t let this be a feature of your boat that you don''t use.
MaryBeth