Review (5/5): Best So Far
I have been using the other battery powered brand for over a decade, and decided to try the Sonicare Xtreme. This model cleans better, and is easier to use. As far as the leakage - the bottom is sealed by an "O-ring" (black plastic ring on the bottom). To keep this seal intact and working, smear a SMALL amount of petroleum jelly on the O-ring all around. This, plus some common sense care has kept our two Sonicare toothbrushes dry and corrosion free.
Update - We have been using the Sonicare Xtreme for almost two years, and here are some tips: Clean the toothbrush head with the head pointing down under the hottest water out of the faucet. Then dry the head shaft and back of the head with the head pointing down. List will eliminate any water seeping into the head base. The head normally last two months, and with standard use, the batteries should last the same.