In many parts of the country groundwater contains high levels of dissolved minerals and is commonly referred to as hard. Groundwater very slowly wears away at the rocks and minerals picking up small amounts of minerals and metals that can be a nuisance in elevated concentrations, but in small enough quantities improves the taste of water. Calcium and magnesium ions are the minerals that make water hard. Water contains traces of minerals that are essential for human health. Though research has found conflicting results relating the mineral content of water to the risk of cardiovascular disease, the majority of studies indicate the lowest risk when minerals in water are highest and highest cardiovascular risk when the water is soft.
Water containing approximately 125 milligrams of calcium, and magnesium per liter of water (ppm) or 7 grains per gallon can begin to have a noticeable impact and is considered hard. (Some label water hard at 100 ppm.) Certainly, concentration of magnesium and calcium above 180 milligrams per liter (10.5 grains per gallon) is considered very hard. As the mineral level climbs, there are observed impacts in our homes. Bath soap combines with the minerals and forms a pasty scum that accumulates on bathtubs and sinks. The minerals also combine with soap in the laundry, and the residue doesn’t rinse well from fabric, leaving clothes dull. Hard water spots appear on everything that is washed in and around the home from dishes and silverware to the floor tiles and car (though commercial car washes use recycled water and are more environmentally friendly).
Many can live with the water spots and soap scum issues by adding vinegar to dishwashers and using hard water formulated shampoos, but are induced to treat their water because of the potential impacts on plumbing and appliances. When heated, calcium carbonate and magnesium carbonate are removed from the water and form a scale (lime scale) in cookware, metal hot water pipes, dishwashers and water heaters. As the scale builds up more energy is required to heat the water and hot water heater and appliances have work harder which will burn them out eventually. Thus, in hard water locations hot water heaters and other appliances have a shorter life. However, softened water increases the potential for leaching heavy metal from pipes, solder, and plumbing fixtures. Increased levels of copper, lead, zinc, and cadmium are found in soft water, particularly when it stands overnight in the plumbing system.
The classic water softening is an ion exchange system consisting of a mineral tank and a brine tank. The water supply pipe is connected to the mineral tank so that water coming into the house must pass through the tank before it can be used. The mineral tank holds small beads of resin that have a negative electrical charge. The calcium and magnesium ions (along with small amounts of other minerals) are positively charged and are attracted to the negatively charged beads. This attraction makes the minerals stick to the beads as the hard water passes through the mineral tank. Sodium is often used to charge the resin beads. As the water is softened, the sodium ions are replaced and small quantities of sodium are released into the softened water, thus the taste and potential health impacts that requires bypassing the kitchen sink or additional treatment.
Eventually the surfaces of the beads in the mineral tank become coated with the calcium and magnesium. To clean the beads, a strong salt solution held in the brine tank is flushed through the mineral tank this occurs two or three times a week and consumes 20-30 gallons of water. Sodium is typically used in the brine tank, but potassium can also be used. The excess sodium solution carrying the calcium and magnesium is typically flushed to the septic system. The amount of sodium in water conditioning systems is a real problem for humans, the septic system and the environment. Softened water is not recommended for watering plants, lawns, and gardens due to its sodium and chlorine content. Water used in recharging a water softener is discharged into the septic tank and soil absorption field if you have a septic system. Otherwise a separate holding tank or discharge, which could be emptied by a vacuum truck would have to be installed into the plumbing system.
Salt water is heavier than fresh water and interferes with the passive functioning of the septic tank. The salt water sinks to the bottom of the tank occupying space that is designed for the settling of heavier solids interfering with the proper formation of layers in the tank and driving the solids and grease into the drainfield. In addition, while some studies have shown that sodium does not interfere with bacterial action in ATU tanks in alternative septic systems, David Pask, Senior Engineering Scientist of the National Small Flows Clearinghouse has seen septic distribution pipes plugged with a “noxious fibrous mass” that was grease and cellulose from toilet paper that only occurred in homes with water softening systems. He felt the brine in the conventional septic tank had interfered with the digestion of the cellulose fibers and might be carried over into the septic systems drain field. Field practitioners reported to the Small Flows Clearinghouse negative impact from water softening regeneration brines. A study involving two adjacent septic field dispersal systems in a shared mound have shown that the trenches that received the septic effluent with water softener brine discharges formed a thick, gelatinous slime layer that clogged the infiltrating surface, while the trenches receiving no salt water discharge remained open with a normal microbial clogging layer.
All of the salt that is released into the septic system and ultimately the leach field and groundwater can impact the ecology. According to the U. S. Environmental Protection Agency, chloride concentration above 180 mg/L interferes with nitrogen fixation in the environment. Chloride concentration in the regeneration discharge can reach into the 10,000 mg/L and sodium concentration can reach 6,000 mg/L. According to Orenco Systems a field study of 18 on-site wastewater treatment systems in Virginia clearly showed that nitrogen removal was inhibited in systems receiving water softener backwash brine.
To solve the taste problem or health concerns associated with drinking softened water reverse osmosis systems are often sold as an accessory item when a whole house water softener is installed or for other actual or imagined problems without proper testing. Waste water from household systems is typically connected to the house drains and will add to the load on the household septic system. This is a significant additional water use and load to the septic system and could impact the life and functioning of your septic system and well since a 5 gallon a day reverse osmosis system might waste 90 gallons a day. The principal uses of reverse osmosis in are for the reduction of high levels of nitrate, lead, mercury, arsenic, cadmium, sulfate, sodium and total dissolved solids.
No treatment is without consequences and an inappropriate treatment could create other problems without providing any measurable benefit. Before considering purchasing any treatment system test your water yourself to get a full picture of the nature of your water supply. Never purchase a water treatment system without first fully testing your water for at least iron, manganese, nitrate, lead, arsenic, fluoride, sulfate, pH, total dissolved solids, hardness, sodium, copper, total coliform bacteria and E. Coli bacteria, appearance, taste and anything else of local concern. (Prince William County is holding a subsidized water clinic on March 31, 2014.)
Personally, I did extensive water testing on my well before I purchased the home to ensure that I could live with the well water without further treatment. This does not guarantee me a lifetime of problem free well water since groundwater is a dynamic system that can vary over time and wells age and do die, but it is a start. If you must soften your water, potassium chloride can be used instead of sodium chloride in a typical water softener. Potassium chloride works exactly the same way that sodium chloride does in the softening process and the potassium chloride reduces the amount of sodium in drinking water, the potassium in the treated water is a necessary mineral and it eliminates the excess sodium in the septic system, drain field and released into the environment, but not the chloride problem. The impact of potassium chloride on septic systems has not been studied. Potassium chloride costs much more than sodium chloride. A forty pound bag of pellets costs about $40 for Potassium chloride and under $8 for sodium chloride.
One final note, though magnetic water softening is sold, according to research done at Purdue University in the 1990’s this method of water conditioning was not effective. Mike R. Powell, P.E., author of an exhaustive discussion of the research relating to magnetic water treatment entitled “Magnetic Water and Fuel Treatment: Myth, Magic, or Mainstream Science?” states “Much of the available laboratory test data imply that magnetic water treatment devices are largely ineffective, yet reports of positive results in industrial settings persist ….” “Consumer Reports magazine tested a … magnetic water treatment device…. Two electric water heaters were installed in the home of one of the Consumer Reports staffers. The hard water (200 ppm) entering one of the heaters was first passed through the magnetic treatment device. The second water heater received untreated water. The water heaters were cut open after more than two years and after more than 10,000 gallons of water were heated by each heater. The tanks were found to contain the same quantity and texture of scale. Consumer Reports concluded that the … unit was ineffective.” I called Consumer Reports to obtain a copy of the article and permission to cite it.. The full 280 word article can be found in the February 1996 volume of Consumer Reports on page 8. It appears that bottom line is, don’t waste your money on magnetic water treatment.