A release that ratepayers were required to sign in order to obtain a partial rebate of illegal water charges was enforceable. The city did not fraudulently conceal facts from ratepayers. Its FAQs said the partial refund was due to the statute of limitations barring claims for any greater refund and revealed that the overcharges had been assessed for a longer period than the refund allowed. The release was not unconscionable as the ratepayers’ right to any refund was contested. There was consideration for the release in the partial payment and it wasn’t necessary anyway as the release was in writing. Civ. Code 1668 didn’t bar the release since it was for a past, not a future, tort.