Electric bath

this is an idea i had one winters evening by the fire, after many a night without a wash. i was stuck out in the middle of nowhere, and i didnt like the idea of a cold river. basically, rather than a conventional bath, which of course you have to run each time, you just keep the water in the bath permanently, which reduces water rates drastically. Then, to heat up the bath, simply turn the dial to the required temperature (much like the dial of a shower, only more efficient). but what about the dirt!!?? i hear you all scream. well, of course there would be dirt in the water, that is, if it wasnt filtered by the electrolysis. what about the evaporation of water??!! i hear you all cry. well, there is a roof to the bath, with tiny pores which collect the droplets, that proceed to drain down to the bath itself. any objections?