Septic tank
While a properly maintained and located septic tank does not pose any more environmental problems than centralized municipal sewage treatment, certain problems can arise with septic tanks in unsuitable locations. Since septic systems require large drainfields, they are not suitable for densely built areas.
Tankhouse
There are far more tankhouses in California than in any other state, and they most probably originated in California. A tankhouse was built in Mendocino, California, in 1857 and many tankhouses in a variety of designs are still standing in that village. Tankhouses can be found in most of the state's 58 counties, wherever there was water not more than 50 feet or so below the surface. Probably after transcontinental and branch railroads were completed, tankhouses were built in other western states, the midwest, and even in the east.