Hard water is notorious for leaving behind dingy, gray laundry stains on light and bright clothing and textiles. Washing laundry with hard water will leave whites and light colors with an overall grayish cast; the laundry may end up looking dirty even after repeated washings. Treating the water to soften it before washing the clothing is the best way to eliminate the problem. A water conditioner for the whole house is one possibility, but the water for each individual load can be treated using common household water softeners like salt or baking soda. Choosing the right laundry detergent will also help eliminate the issues resulting from washing laundry with hard water.

The minerals in hard water will vary, depending on geography. The best way to tell if hard water is a problem is to look at the white and light-colored laundry. Items that have been washed in hard water and left to sit in the washing machine will often show signs of rust, usually in the form of small dots shaped like the machine's drainage holes. An overall dull, gray appearance is another sign of washing laundry with hard water. Repeated washing will not eliminate the gray discoloration, unless the hard water is softened first.

Conditioning or softening the water that enters the home is the most convenient way to eliminate the problems caused by washing laundry with hard water. Installing a water softening system should improve the quality of the water used for drinking, bathing, and laundry, but it can be expensive. Adding a water conditioner to the washing machine before adding the laundry will soften the water enough to improve the outcome without a huge investment. Water softener or conditioner is sold in the laundry section of home-improvement and big-box stores. If desired, table salt or baking soda can be used to soften the water instead of a conditioning formula.

Once the water has been conditioned, choosing the right detergent will help eliminate the damage caused by washing laundry with hard water. A true detergent is the best choice; soap-based and handmade laundry soap may not react well when used for laundry with hard water. Washing the laundry at the temperature recommended by the detergent manufacturer will yield the best results. In many cases, washing laundry with hard water requires using the hottest setting possible to fully dissolve the detergent and clean the clothing.