And you'll be getting lots of sediment, organic bits n pieces, etc. in your tank that you can never clean out again. So even with sanitizing, you're leaving lots of fertilizer that will allow things to grow fast as soon as the sanitizer is used up. Ask any pool owner how fast their really clean pool can turn green without constant chlorination, just via dirt from the sky. At best, your water will constantly smell swampy. And there is the risk of e.coli, "beaver fever", and all the rest that can come with under-treated water if you do accidentally wash dishes, hands, teeth with it. Plus constantly unplugging things that may tend to get plugged easier due to the crud.