When they do not work to capacity, some of their load is dumped on the liver. One of the liver's primary functions is to metabolize stored fat into usable energy for the body. But if the liver has to do some of the kidney's work, it cannot work at full throttle. Drinking an adequate amount of water every day is the best treatment for fluid retention. This water can show up as swollen feet, hands and legs.
Diuretics only offer a temporary solution at best.
They force out stored water along with some essential nutrients. Again, the body perceives a threat and will replace the lost water at the first opportunity. Thus, the condition quickly returns. Your body will only tolerate sodium in certain concentrations. The more salt you eat, the more water your system retains to dilute it.