I think hypothetically when the system is first installed it's supposed to be tested, but I don't put a lot of faith in that. Interestingly, in contrast to parent, it's pretty standard for the water to be totally unfiltered. Generally, you have an electric pump that cuts on any time the water pressure drops below a certain level to maintain it. Honestly I've no idea how much it costs me a month, but it's pretty nominal. My electric bill runs about $125/mo and most of that is the AC.
(In case you were wondering, sewer is dealt with via a septic system, which still amazes me. All your wastewater drains into a ~1000 gallon tank buried in the ground. At the top of the tank are field lines, which distribute water and drain it over a wide area. Solids are rapidly broken down by bacteria in the tank and quickly dissolve. These systems can be maintenance-free for 25 years, though the septic industry recommends you pump them every several years to remove "sludge" that slowly accumulates at the bottom.)