This is a VERY BAD DEAL -- almost pure profit to them, obtained by targeting people who are afraid of unexpected expenses. The basic design -- only the waterline -- and the fine print on this one means that you are very unlikely to ever be able to claim against this policy. Check it out (4 page pdf).
Whenever you are approached or sent a mailer selling insurance that only covers a specific risk and that gives you a pitch that plays on your fear of unexpected bills, you should immediately be suspicious. Reputable insurance companies do not sell products like this, particularly with exclusions that gut the coverage. Insurance is too important to let yourself be scammed.
If you are in Oregon or especially in the Salem area, I would be happy to review any offers you get like this to help you understand the coverage and the alternatives for managing the risks discussed.