How a water softener works and available alternatives

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Water is thought to be “Hard” if it contains a lot of dissolved calcium or magnesium. The measure of how “Hard” the water is determined by a simple water test that yields a Hard Water Count in “Grains” of hardness. The higher the number – the harder your water is.

Hard water causes two main problems in our homes:

• 1. It can cause “scale” to form on the inside of pipes, water heaters, tea kettles and so on. The calcium and magnesium precipitates out of the water through everyday use and when it does it sticks to things. The scale doesn’t conduct heat well, and it also reduces the flow through pipes. Eventually, pipes can become completely clogged. This problem is exaggerated in a water heater where flash heating causes large amounts of dissolved minerals to precipitate out.

• 2. Hard water reacts with soap to form a sticky soap scum, and also reduces the soap’s ability to lather. Since most of us like to wash with soap, hard water makes a bath or shower less productive. Often wash becomes dull and whites are difficult to keep white.

The absence of calcium and magnesium in water is “Soft” by definition. The solution to hard water is either to filter the water by distillation or reverse osmosis to remove the calcium and magnesium, or to use a water softener. Filtration is extremely expensive to use for all the water in a house, so a water softener is usually a less costly solution. Point-of-use reverse osmosis systems (RO) are commonly used in a home to provide a single small faucet of RO water, and it is often plumbed to a fridge so that homeowners are able to use RO water as drinking water. Owing to the cost of the system itself, as well as the regular maintenance to clean the filters and keep the RO media effective, RO whole house systems are uncommon.

A common household appliance is a salt based water softener. The idea behind a water softener is simple. The calcium and magnesium ions in the water are replaced with sodium ions. Since sodium does not precipitate out in pipes or react badly with soap, both of the problems of hard water are eliminated. To do the ion replacement, the water in the house runs through a bed of small plastic beads or through a chemical matrix called “zeolite”. The beads or zeolite are covered with sodium ions. As the water flows past the sodium ions, they swap places with the calcium and magnesium ions. Eventually, the beads or zeolite contain nothing but calcium and magnesium and no sodium, and at this point they stop softening the water. It is then time to regenerate the beads or zeolite.

Regeneration of a water softening system involves soaking the beads or zeolite in a stream of sodium ions. Salt is sodium chloride, so the water softener mixes up a very strong brine solution and flushes it through the zeolite or beads (this is why you must add salt to your water softener). The strong brine displaces all of the calcium and magnesium that has built up in the zeolite or beads and replaces it again with sodium. The remaining brine plus all of the calcium and magnesium is flushed out through a drain pipe.

This process of regeneration creates a lot of salty water, often more than 25 gallons (95 liters) per regeneration cycle. From an ecological perspective this is quite a cost as municipal water treatment facilities must clean the salt and other dissolved solids from the water in order to make it potable. So in addition to the sheer quantity of water flushed regularly as waste water, we must also contend with large quantities of salt added to our potable water.

When you consider that less than 1% of the water on earth is drinkable this becomes all the more alarming. Many municipalities are regulating the use of water softeners, and in some cases, have banned the use of salt based water softeners all together.

So if you own a tankless system and do not have a water softener or do not want to damage our local ecology there are alternatives. Aside from RO systems and various media filter systems commonly available, a new class of electric water “Conditioners” is now available. These water conditioning systems claim to add ions to water and these added ions prevent the dissolved calcium and magnesium that may be present in water from reacting with pipes and other metal surfaces and thus the hard water sludge does not precipitate out and cause typical hard water problems. Many tank and tankless manufacturers are endorsing this new technology despite an ongoing campaign by traditionalists who seek conclusive proof that water conditioners actually work.

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