As a home owner you should identify and tag the water supply turn off valve for the entire house. Then look for the turn off for each fixture. There should be a shut off for each toilet, one for the cold water inlet for the water heater, and there may be shut offs under the sinks. Identify the main gas valve turn off and each appliance shut off.
Periodically, all facets, hose bibs, and other valve should be checked for leaks. Run the water, look under the sink cabinets for leaks, and then go into the basement or crawl space to determine if any leaks exist there.
Water closet flushing systems frequently waste water. Remove the top of the flash tank of the toilet periodically to check its operation. Listen to the toilet to determine if there are any leaks in the reservoir. These leaks are usually in expensive to repair.
Check the toilet bowl to see that it is tight to the floor. If the toilet bowl is loose, a new wax seal may be required.
In cold climates, drain exterior water lines, hose bibs, and sprinklers in the winter. Turn the valve to the hose bib off on the inside of the house and turn the outside hose bib valve on.
Locate the water heater and read the instructions in the booklet or on the side of the water heater. Depending on the manufacturing specifications, drain 2 or 3 gallons of water from the heater every 3 to 4 months to remove sediment that may have accumulated in the bottom of the tank. If this valve has not been opened in some length of time, they may not seal properly when closed and a new washer may be required.
All valves in the home should be operated periodically. If these valves appear corroded, they should be cleaned and checked for leaks. If they are corroded, there is a good chance that they may leak after you clean and operate then. Therefore, it would be wise to start at the main water turn off to the house and water heater, then approach the individual valves.
You may or may not have a sump pump in your home. There are different uses for sump pumps. A clear water sump pump removed groundwater that accumulates around the house. There is usually a drain tile system that runs into a sump pump crock. The sump pump discharge is water through a pipe to the exterior of the house. Most communities do not allow this water to be discharged into a sewer system. A sanitary sump pump is used to discharge gray water into a septic or sewer system. This is usually water from my washing machine or basement sink.