Difference Between Hard Water and Soft Water

Medically Reviewed by Christine Mikstas, RD, LD on July 12, 2023
3 min read

You may have heard water referred to as being either hard or soft, but what does that really mean? The mineral content of water affects how it is classified on a scale ranging from hard to soft.

All water is not created equal. Around 85% of the US water supply is hard, but many businesses and homeowners utilize water softeners to strip away extra minerals. But which one is better for you, hard water or soft water?‌

The hardness or softness of water is determined by the mineral content of both calcium and magnesium

  • Soft water has less than 17 parts per million
  • Slightly hard water has 17 to 60 parts per million
  • Moderately hard water has 60 to 120 parts per million
  • Hard water has 120 to 180 parts per million‌
  • Very hard water has greater than 180 parts per million 

Both types of water offer unique risks and benefits, and water quality may vary for both hard and soft water. It usually comes down to personal preference and what you’re using the water for. There is a lot of information out there about hard and soft water, but some of it is just myths or misunderstandings.

Understanding contamination. Hard water contains more minerals, but that doesn’t mean it’s contaminated. Contamination is different than mineral content and refers to germs and bacteria instead. Minerals are valuable nutrients for your body, although too many may pose health risks.‌‌

Clogged pipes. Some people believe that hard water can clog the pipes in your home. A long time ago, when homes were built using galvanized steel, excessive levels of magnesium and calcium did stick to the inside of the pipes. So if you have an older home built from the mid-1940s to the mid-1970s, this may be a cause for concern. Otherwise, it’s not something you need to worry about.‌

Water taste. Interestingly enough, hard water is thought to taste worse because of its higher mineral content. In reality, softer water is more likely to taste different than what you’re used to. Minerals improve water’s taste, while softer water lacks these taste differentiators. If your water is softened using a chemical or filtration system, it may taste slightly salty.‌

Soft water is better. Many people believe that soft water offers a better clean for your body and your home because it doesn’t leave behind a mineral residue like hard water can. But the truth is that neither type of water offers a better or worse clean. However, soft water may leave you feeling like there’s a residue because the lack of minerals makes skin feel slippery.

Rainwater is hard. Water that falls from the sky starts out soft because it cannot carry as many minerals during evaporation. However, as it flows along the ground, it picks up minerals along the way.‌

Mineral intake. Most of the time, added minerals are good for your body. However, in some cases they may pose health risks. Too much magnesium may lead to renal issues and diarrhea, similar to a laxative effect.

If you’re concerned that your water is too hard, there are several options for softening it. Keep in mind that water softeners are not water filters and don’t usually remove any contaminants from your water.‌

Ion exchange. This technology uses a physical and chemical process to filter your water through resin or zeolite. Positively charged sodium ions attract calcium and magnesium, removing it from your water.‌

Eventually, the resin in an ion filter reaches its maximum capacity and stops working. Using a reverse flush technique, you can rinse the brine from inside the filter to continue using it effectively.‌

Choosing a model. You can choose a timed water softener that is programmable to filter water during certain times of the day and regenerate during other times. Alternately, you can choose a model that requires manual operation for switching between the two modes.‌

Maintaining your softener. Don’t assume that your water softener is always working correctly. Each model requires regular maintenance to monitor clogs and clean the filtering mechanism. This is also important since bacteria and fungi may accumulate in the filter over time and need removal.