Our neighbor has a kitchen water filter and her water tastes better. What types of water filters are best for flavor and safety and do they cost much to operate?—Ann T.

Answer

Even if your water is from a public supply, it may still contain small amounts of contaminants. There’s always a possibility that by the time the water reaches your house, the chlorine level may have often dropped to the point where it may have gotten reinfected en route. It may not be a bad idea to first have your water tested.

Although there are many specific models, brands, and trade names of water filters, the basic options can be broken down into distillation, reverse osmosis (RO), ozone, ultraviolet light (UV), and carbon. Each type has its advantages for improving various water problems.

Countertop electric distillers are effective for improving most common water problems and removing most contaminants. Since the water boils during the distillation process, it is also disinfected. The water vapor condenses and drips into a gallon jug. Once the jug is filled, store it in your refrigerator.

RO systems are also effective for most common drinking water problems, and they produce filtered water as you use it. This eliminates the chances of recontamination when the filtered water is stored.

These units use an RO membrane that acts like a super-sieve to filter out almost everything in the water. Most units also have pre- and post-carbon filter cartridges to remove chemicals. The only drawback is that these units use more water than is actually purified, so some water is wasted.

Ozone gas purifiers are extremely effective and leave no residual chemicals in the water. Many municipal water plants now treat all their water with ozone gas. In addition to killing bacteria, cysts, and viruses, it improves the taste. Ozone quickly dissipates from the water, so there are no harmful health effects from it. UV purifiers pass an intense light beam through the flow of water inside the unit.

Small portable ozone purifiers are also ideal for camping or during emergencies. Hang the tube and bubble stone into a jug of water and switch it on. Another good use is to purify and clean fresh fruits and vegetables. Fill your sink with water, then place the food and bubble stone in for a few minutes.

Carbon filters improve flavor and remove some chemicals. To filter out impurities, a solid carbon block is better than a granular carbon filter. Granular ones are often used as post-filters for other types of filters. Consider a mini-RO unit (quick-disconnect aerator) for use on kitchen faucets.

The important thing to remember for a water filtering system that uses a replacement filter is to replace the filter when it is time. Most systems provide some type of indicator.

The utility bills cost to operate a water filter depends on the specific design. Distillers, since they use electricity to boil the water, will push up your electric bills the most—about 25 cents per gallon. In the winter, this electricity ends up as heat in your house, so the net cost is much lower. In the summer, use it in your garage or other unconditioned space.

Ozone generator units use a small corona discharge ozone generator. To purify one gallon of water, it is recommended to run it for 15 minutes. At only 24 watts, this costs less than a penny per gallon. Ultraviolet water purifiers also use only about 30 watts of electricity. Many replacement carbon filter elements are priced in the $20 range.