By Rehan Iqbal
Hard water causes all kinds of problems. It leaves mineral deposits on plumbing, makes tubs and sinks harder to clean, keeps soap from working and even forms tea scum. How can you fix your water? By installing a water softener. There are two technologies to choose from: salt-based ion exchange softeners and salt free water softeners. What’s the difference between these systems, and which one is right for you?
When water passes through some types of rock, it picks up hardness minerals. In particular, water from aquifers that have limestone, chalk or gypsum contain dissolved calcium carbonate, magnesium carbonate, bicarbonates and sulfates. These chemicals cause several issues.
Calcium carbonate, magnesium hydroxide and calcium sulfate in hard water sticks to plumbing, creating scale. Over time, this buildup will clog pipes. Calcium precipitates out of heated water, leading to even more buildup in water heaters. This is also what leaves scale on tea kettles and coffee makers.
Ions react with soap, reducing its surfactant properties. This turns sodium stearate into calcium stearate, a solid precipitate that makes up soap scum. This keeps the soap from lathering, and leaves deposits on surrounding surfaces.
How Do I Know if My Water is Hard, and When Should I Treat It?
If you think your water supply is hard, you can find out the hardness with a DIY hard water test kit. These kits use test strips that react to the minerals in the water. These strips must be kept in a water tight container, and your hands must be dry when handling the strips. Otherwise, contamination may give you a false resort. Shortly after exposure to water, the strip changes color. This color indicates the water’s hardness.
Most water softeners are rated by Grains Per Gallon (GPG,) while test strips use either GPG or Parts Per Million (PPM) for hardness measurements. 1 GPG is equal to about 17 PPM, or 3 GPG per 50 PPM. If your water has a mineral content of one GPS or less, it’s considered soft water. Water containing between 1 and 7 GPG is moderately hard, 7 to 10 GPG is hard and over 10 GPG is very hard.
What does this mean in real world use? You probably won’t notice any problems with water that has a hardness of 3.5 GPG or less. Between 3.5 and 7 GPG, you may notice some staining, and your skin may feel dry after a shower. At this level of hardness, a water softener is optional. At 7 to 10.5 GPG, you’ll start noticing problems with plumbing and appliances. Thanks to their high operating temperatures, on demand and tankless water heaters will have trouble with mineral deposits. UV water filters can’t get good light penetration with water this hard, making them ineffective at killing pathogens.
At 14 GPG and above, staining around faucets becomes a major headache. Mineral buildup will damage plumbing and water-based appliances, including tank water heaters, washing machines, dish washers and ice makers. If you have very hard water, you will easily recover the cost of a water softening system by reducing damage to appliances caused by scale buildup.
Salt-based systems use a process called ion exchange to remove minerals from water. Ion exchange softeners are the most popular solution for hard water, thanks to their long history on the market and their ability to treat water of any hardness. This salt based process uses two tanks. The first tank contains a positively-charged resin bed saturated with sodium ions. This is where the filtration takes place. The second tank, called the brine tank, contains salty water.
As water passes through the first tank, the resin attracts negatively-charged mineral ions. These minerals swap places with the sodium ions, staying in the resin bed. While this sounds like it would make the water salty, the sodium added in this process is minimal. On average, a fluid ounce of salt-treated water only contains 1.6 mg of sodium. To put that in perspective, to get as much sodium as a teaspoon of table salt, you would need to drink about 190 8 ounce glasses of water.
Eventually, calcium and magnesium will replace all of the sodium on the media. Once the media reaches this saturation point, it needs to be regenerated. This is handled automatically by a controller. Older systems use time-based controllers, activating an electronic valve to regenerate the media on a regular schedule, usually in the middle of the night.
The installer has to calculate your average water use and hardness to estimate when the media needs to be regenerated. Modern systems use an electronic metered valve, measuring flow through the system and regenerating when the media is depleted. This cuts down on salt usage and water drainage. Like metered systems, this cleaning cycle can be set up for a specific time slot. This way, the electronic valve cycle won’t activate when you need water.
The brine tank can be pre-fill or post-fill. Cheaper systems use a pre-fill tank, adding water when the regeneration cycle starts. Once the tank is full, the system waits until the water has time to absorb the salt. Post-fill systems always leave some water in the tank, so there’s brine ready to recharge the media. This brine runs through the media tank, forcing the ion exchange process to run in the reverse of normal operation.
Now, the sodium attaches to the media, and the hard water minerals are released into the water. The minerals dissolve into the brine, and this super hard water is flushed out of a drain line. Finally, the media tank is flushed with fresh water to remove any residual minerals before going back online.
The size of this system depends on the size of the home and the hardness of the water. Correctly sized, a water softener should only need to regenerate once every few days.
If you’re only dealing with mild water hardness, you may not need to deal with the complexity and maintenance of an ion-exchange system. Saltless water softeners don’t actually do any water softening, since the minerals aren’t removed. Instead, these water conditioners change the form of hard water minerals to make them harmless.
These water softeners use Template-Assisted Crystallization (TAC) media. The water conditioner tank has a polymer resin bed. As calcium carbonate and magnesium carbonate pass through the filter, they attach to the media. This process, called Nucleation Assisted Crystallization (NAC,) forms crystals, carbon dioxide and water.
Once a mineral molecule attaches to a nucleation point, it kicks off a chemical reaction, crystallizing minerals in the water. More mineral molecules fall out of suspension to join the crystal. Eventually, the hardness crystal gets so big that it falls off of the media.
Once the water passes through the fiberglass resin tank, it’s still hard, since calcium and magnesium are still present. However, these crystals won’t react with plumbing or soap, passing harmlessly through the system and down the drain. Meanwhile, the carbon dioxide from this process forms microscopic bubbles that scrub the inside of pipes. By the time you need to replace your media, your pipes will be cleaner than they were when the system was installed.
Since water conditioning doesn’t need salt for crystallization, it doesn’t affect the PH of the water. This passive filtration system also doesn’t need to be backflushed, and doesn’t require additional chemicals. This conserves water and reduces operating costs. Some areas ban backflushing of ion exchange systems, to keep salt from contaminating streams and ground water. If this is the case in your area, a saltless water softener is your best choice for controlling water hardness.
Over time, the media in a salt free conditioner break down from the physical process of crystallization. On average, this media needs to be replaced every 5 to 10 years. Salt free water conditioners are also sensitive to clogging. Most quality conditioners come with a built-in sediment filter. This filter needs to be flushed or replaced occasionally.
Condensation on the tank can be an issue, leading to puddles around the system. Adding a neoprene sleeve allows the water to evaporate before it can collect on the floor. White the up front cost of this type of water softener is high, lifetime costs are lower than a salt based system, since it doesn’t require salt or backflushing. However, ion exchange systems will always outperform salt free systems, making them a better choice for very hard water.
Can magnets soften water? No, but they can keep deposits from forming, much like salt free systems. Magnets are commonly used in industrial settings to treat calcium in water. The magnets charge the calcium particles, so they won’t bond with each other. This bonding is what causes calcium to build up on pipes. This charge lasts about 72 hours, which is usually enough time for the water to pass through the plumbing system. Unlike nucleation or salt based technology, this process doesn’t affect other hardness minerals.
Do home magnetic water softeners work? Sometimes. There are plenty of gimmick devices that are little more than a pair of permanent magnets or a tiny electromagnet. These devices don’t have the strength to charge calcium. Effective full house devices use several feet of electrically charged wire wrapped around the water main. Even then, their use is limited to moderately hard water. However, they can be used in tandem with an ion exchange system, reducing the amount of salt needed to stop problems related to hard water.
Why Does the Water Feel Slimy After Installing a Water Softener?
This is the most common complaint people have once they install a water softener. There are two reasons this can happen. Most salt-based softener systems are set from the factory to deal with very hard water. If your water hardness is lower than the softener’s settings, it’s going to add too much salt.
If too many sodium particles are left in the water, it makes that water feel slippery. Changing the softener settings is usually enough to correct the problem. In some cases, it makes sense to mix in some untreated water to raise the hardness to an acceptable level. Some systems have a built-in bypass valve, or an external valve can be added to the plumbing loop.
Unlike their salt based counterparts, nucleation-based conditioners don’t make changes to the water minerals. However, the water can feel slick when you’re using soap. Whether you’re using a resin or saltwater softener, the resulting water isn’t reacting with soap, making it more effective. If you keep using the same amount of soap, shampoo or detergent you did with hard water, it will be harder to wash off.