Water itself doesn't stain fabrics; the mineral ingredients in the water are what cause the stains. Homes on private wells are more likely to have hard water, iron and manganese issues, whereas public water supplies typically include calcium and magnesium, which may not cause hard water stains unless the home's hot water heater has formed rust inside. Each of these stains require separate treatment methods.
Laundry Rust Remover
If you have clothes stained with black, brown, yellow or ocher colored streaks, the next time you wash your clothes, add a rust remover product designed for use in the laundry. Do not use household bleach on these types of stains, because it just makes them worse by deepening the colors. To keep iron particles in a suspended state in the water instead of dispersing them throughout the laundry, add a water-softening product to both the wash and rinse cycles of the washer. For other stains, use products you already have at home to remove them, and then run them through a laundry cycle in your machine.
Dried Water Stains
Dried water stains are a different beast altogether. When water splashes on fabrics, sometimes it dries and leaves a water spot. These types of water stains are easy to remove with one of several methods. With items that can be laundered, you can run them through the wash cycle to remove water spots.
Moisten and Iron
Water-spotted cotton and iron-safe fabrics: Place the item, turned inside out, on an ironing board with the stain centered over a dry white towel. Moisten the stained area with a damp washcloth. Adjust the iron to the heat setting for the fabric type. Iron the dampened area until dry. Move the clothing so that the stained portion lays atop the dry portion of the towel, and continue ironing. Remoisten and iron the stained area until it disappears. If the fabric still sports a ring where the water spot was, turn the fabric inside out and rub it with a spoon.
Items such as upholstery or drapes that cannot be washed require a different method. Wet the water stain with a damp cloth. Fold several paper towels together until they are about 1/8 inch thick. Set them atop the stain. Keep them in place by adding a heavy object such as a heavy glass bowl or pot. Set up a fan to dry the fabric. You can also use a hair dryer set to cool air to help dry out the stain.
Before using the vinegar method, test the vinegar on a hidden part of the fabric, such as inside on a seam, because vinegar can fade some fabrics. Place a washcloth under the faucet to wet it; wring it out. Moisten the water-spotted area with the damp washcloth. Dampen the corner of another washcloth with white distilled vinegar, and rub the stained area to remove the water spot or ring. Rinse out the first cloth again under running water; wring it out and reapply it to the area to remove the vinegar. Let the stained area dry. Repeat as necessary.
A handheld steam machine provides a quick solution for water-spot removal, whether on clothes, upholstery or other fabrics. If you don't have a garment steamer, use the steam setting on your iron. Blast the water stain with a burst of steam to remove the spot, and let it dry. If you use an iron, verify that it emits steam only and not drops of water and steam, because these drops will create more water stains.
Preventing Stained Laundry
If your home is on a well, you'll constantly battle black, brown, yellow or ocher stains showing up on laundry once they appear, unless you install a whole-house iron filtration system. If your hot water appears rusty, empty the hot water heater by attaching a hose to the drain bib. Flush it several times until the water runs clean.