I'm sure you've heard the terms 'hard water' and 'soft water', but do
you know what they mean? Is one type of water somehow better than the
other? What type of water do you have? Let's take a look at the
definitions of these terms and how they relate to water in everyday
life.
What is Hard Water?
Hard water is any water containing an appreciable quantity of dissolved minerals.
What is Soft Water?
Soft water is treated water in which the only cation (positively charged ion) is sodium.
The minerals in water give it a characteristic taste. Some natural
mineral waters are highly sought for their flavor and the health
benefits they may confer. Soft water, on the other hand, may taste
salty and may not be suitable for drinking.
If soft water tastes bad, then why might you use a water softener? The
answer is that extremely hard water may shorten the life of plumbing
and lessen the effectiveness of certain cleaning agents.
When hard water is heated, the carbonates precipitate out of solution,
forming scale in pipes and tea kettles. In addition to narrowing and
potentially clogging the pipes, scale prevents efficient heat transfer,
so a water heater with scale will have to use a lot of energy to give
you hot water. Soap is less effective in hard water because its reacts
to form the calcium or magnesium salt of the organic acid of the soap.
These salts are insoluble and form grayish soap scum, but no cleansing
lather. Detergents, on the other hand, lather in both hard and soft
water. Calcium and magnesium salts of the detergent's organic acids
form, but these salts are soluble in water.
Hard water can be softened (have its minerals removed) by treating it
with lime or by passing it over an ion exchange resin. The ion exchange
resins are complex sodium salts. Water flows over the resin surface,
dissolving the sodium. The calcium, magnesium, and other cations
precipitate onto the resin surface. Sodium goes into the water, but the
other cations stay with the resin. Very hard water will end up tasting
saltier than water that had fewer dissolved minerals.
Most of the ions have been removed in soft water, but sodium and
various anions (negatively charged ions) still remain. Water can be
de-ionized by using a resin that replaces cations with hydrogen and
anions with hydroxide. With this type of resin, the cations stick to
the resin and the hydrogen and hydroxide that are released combine to
form pure water.
Hard Water Problems
Laundering in Hard Water
Clothes washed in hard water often look dingy and feel harsh and
scratchy. The hardness minerals combine with some soils to form
insoluble salts, making them difficult to remove. Soil on clothes can
introduce even more hardness minerals into the wash water. Continuous
laundering in hard water can damage fibers and shorten the life of
clothes by up to 40 percent.
Bathing in Hard Water
Bathing with soap in hard water leaves a film of sticky soap curd on
the skin. The film may prevent removal of soil and bacteria. Soap curd
interferes with the return of skin to its normal, slightly acid
condition, and may lead to irritation. Soap curd on hair may make it
dull, lifeless and difficult to manage.
Problems with Hard Water in Water Boiler Systems and Pipework
Hard water also contributes to inefficient and costly operation of
water-using appliances. Heated hard water forms a scale of calcium and
magnesium minerals (limescale deposits) that can contribute to the
inefficient operation or failure of water-using appliances. Pipes can
become clogged with scale that reduces water flow and ultimately
requires pipe replacement. Limescale has been known to increase energy
bills by up to 25%.
Limescale in Solar Heating Systems
Solar heating, often used for heating swimming pools is prone to
limescale buildup, which can reduce the efficiency of the electronic
pump. This, in turn can cause the overall system performance to
deteriorate.
How Does Your Water Measure Up?
Slightly Hard
Moderately Hard
Hard
Very Hard
0.3 grains
4-7 grains
8-10
10 grains plus
17.1-51.3 ppm or mg/L
68.4-119.7 ppm or mg/L
136.8-171 ppm or mg/L
188.1 ppm or mg/L plus
Do I have Hard Water?
For municipal water, call your water provider. They can tell you the
average hardness and iron levels. If you have a private well, you can
send us a water sample and we will test it FREE and review your
options. Use this chart to estimate water softener size. To calculate
total hardness, multiply total dissolved iron x 3, then add to total
hardness.
Picking the right water softener is an important step in the
purification of your water. A water softener trades "hard" minerals in
water for "soft" minerals. The typical trade is as calcium (hard
mineral) enter a water softener it is traded for sodium (soft mineral).
Inside a water softener are a bunch of chemical magnets called "ion
exchange resin". These little chemical magnets do the trading. The more
chemical magnets you have in a softener, the higher the capacity is.
Capacity is the amount of gallons a softener will purify before you
need to recharge (regenerate) it.
Capacity of water softeners are measured in "grains" or "grain
removal". This is a chemical measurement that has been used for a long
time. One "grain per gallon" is equal to 17.1 parts per million. The
average water in the United States has 10 grains of hardness per
gallon. You can calculate the exact amount of hardness you have in your
water using a water softener test kit. To calculate how much water you
need to purify, multiply the number of people in your house by 80 (the
average person uses 80 gallons of water per day). Then multiply that
number by 1.5 for a safety factor. For an average family of 4 the
calculation would look like this:
People
4
Gallons per person
80
Gallons used per day
4 x 80 = 320
Safety factor
(x 1.5) = 480
Grains of hardness
10
Total grains used per day
4800
Most homes use a one cubic foot water softener (1 ft3). Each cubic foot
of resin will remove 30,000 to 36,000 grains of hardness. Each cubic
foot will also flow 5 gallons per minute (g.p.m.). In selecting the
right softener using the example above you would pick either a 30,000
grain softener and regenerate it about once a week, or pick a 60,000
grain softener and regenerate it about every 2 weeks.
Regeneration is done using a timer (regenerates after a given time has
passed) or by a meter valve (regenerates after a given amount of water
is purified). A meter softener is the most efficient because if you use
less water, it will regenerate less. A timer based softener is cleaner
because the regeneration process cleans the resin and if you do not use
a lot of water bacteria can accumulate inside the softener.
Regenerating the softener at least once a week will help keep bacteria
in control. `
