Monday, June 19, 2017

Hard Water

In many parts of the country (including mine) the water 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 calcium and magnesium ions. In the water clinics we run here in Prince William county, we have found almost 38% of homes tested in the 2012-2015 water clinics had water softeners, many of these systems unnecessary. Water softening systems have been oversold. Before considering treating your water test it to get a full picture of the nature of your water supply. While these hard water minerals are harmless to human health, but they do cause household problems. However, no treatment is without consequences and an inappropriate treatment could create other problems.

Water hardness are either reported in milligrams per liter(mg/L) or grains per gallon (gpg). Water containing approximately 125 milligrams of calcium, magnesium and iron per liter of water or 7 grains per gallon can begin to have a noticeable impact and is considered hard. Concentration of magnesium and calcium above 180 milligrams per liter or 10.5 grains per gallon is considered very hard. As the mineral level climbs impacts become noticeable. These minerals combine with soap in the laundry and bath soap to form a pasty scum that accumulates on bathtubs and sinks, and 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). When heated, calcium carbonate and magnesium carbonate are removed from the water and form a scale (lime scale) in cookware, hot water pipes, 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. 

There are a number of simple things you can do to reduce the effects of hard water in your home, without having to resort to treating your water, so called softening. My water has elevated levels of calcium and magnesium 170 milligrams per liter yet I do not have a whole house water softener. The simple things to do to address hard water are:
  • Choose a detergent based laundry product. Some laundry detergents/soaps do not produce as many suds in hard water, these are likely to be soap-based products and do not work as well in hard-water as detergent based products. These days, there are laundering powders and liquids available for a wide range of water hardness. Occasionally running your washing machine with vinegar and hot water will clear out the buildup of lime scale.
  • Reduce the temperature of your hot water heater. When water temperature increases, more mineral deposits will appear in your dishwasher, hot water tank and pipes. By reducing the temperature, you will save money and will reduce the amount of mineral build-up in your pipes and tank. Use rinse agents to remove mineral deposits. There are low pH (acidic) products available to remove mineral deposits from pots and pans and dishwasher. 
  • Alternatively, you can use plain white vinegar by using the dishwasher dispenser or placing a cup of vinegar on the dishwasher rack. Boil some white vinegar in your kettle to remove hard water deposits. Drain and rinse your hot water heater annually.

In days past, at the first sign of hard water, domestic water supplies were commonly softened by using a salt based conventional water softening system. Water softening is basically an ion exchange system. The water softening system consists 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 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.

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. Sodium is typically used and is cheap, but potassium can also be used. The salt ions also have a positive electrical charge, just not quite as strong as that of calcium and magnesium, but the high concentration of salt ions overpowers the calcium and magnesium ions and drives them off of the beads and into the solution. The excess sodium solution carrying the calcium and magnesium is flushed to the septic system and into the environment. Some sodium ions remain in the tank attached to the surfaces of the beads and the resin is now regenerated and ready to continue softening the water.

The amount of sodium in water conditioning systems is a real problem for humans and the environment. All of the salt is released into the septic system and ultimately the leach field and groundwater, and these conventional salt-based water softening systems contribute to three problems:
  1. The brine backwash can cause salt buildup in groundwater and other aquatic environments. Water softeners release sodium chloride and other chloride salts into the environment. This can adversely affect groundwater aquifers, streams and rivers. This can add to problems in areas that are already suffering from high concentrations of salts due to road salt application.
  2. Brine backwash in the conventional septic tank had interfered with the digestion of the cellulose fibers and reduced scum layer development, carryover of solids and grease to the distribution system.
  3. The brine back wash system uses water to flush itself out regularly. The EPA estimates in that a conventional softener can use up to 10,000 gallons per year for the backwash cycle. This could be a significant increase in water use for well owners. 
In addition softened water should not be used to water house plants, the salt build up will eventually kill them and they will not thrive. Softened water should also not be used in steam irons or evaporators like evaporative coolers. 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 brine.

Terry Bounds, an engineer, in an article published in the summer 1994 issue of Small Flows (the precursor of the Small Flows Quarterly magazine) states that in his work he has seen noticeable differences between septic tanks with and without water softener brine discharges. Mr. Bounds said that in the tanks with added water softener discharge, he saw reduced scum layer development, carryover of solids and grease to the distribution system, and a less distinguishable "clear zone" that might mean solids remain suspended instead of settling in the tank.

Personally, I do not care to add all that sodium to my diet while removing calcium carbonate and magnesium (something that is also sold in pill form for stronger bones). If you are on public water, you should not need to soften your water. If you must soften your water there may be other options- which I will discuss in a future post.

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