For kidneys to filter, they first take in a high blood flow. Water is an important part of your blood traveling freely to your kidneys. When you’re dehydrated, your blood becomes more concentrated and your heart works harder to circulate less of it through your body. When you’re severely dehydrated, you can do permanent damage to your kidneys. So if you’re losing fluids, it’s especially important to stay on top of drinking water.
Kidney stones and urinary tract infections also do lasting damage to kidneys and can be avoided by staying hydrated. Kidney stones are less likely to form when water is working to prevent the crystals from sticking together. Water also helps flush out the bacteria that would cause an infection in your urinary tract. Also if you do get diagnosed with a UTI, make sure to drink lots of water to absorb the antibiotics given to treat it.