A labeled, accessible valve is useful only when its identity and condition are understood.
The short answer
Ask a qualified provider or DWWD, as appropriate, to identify the household control and the utility boundary. Record its location and safe operation. Do not force, dismantle, or operate an unknown valve, especially near a meter or street-side equipment.
What to notice
Make access ordinary
Keep a clear path, provide light, and ensure an authorized household member can reach the known control. A valve behind fixed storage or a locked room can cost time during a leak. The home plumbing map should distinguish the main from fixture valves and show who to contact if the main does not operate.
Test only with a plan
An old valve can leak or fail when moved. Have a qualified provider assess it and explain an appropriate test under controlled conditions. Confirm how complete closure is checked, how the system is returned to service, and what to do if the valve will not close. Avoid using an emergency as the first trial.
Plan replacement as controlled work
Ask what water interruption, utility coordination, permit, access, and downstream testing are involved. Clarify whether the proposal concerns a property valve or utility-owned control. After work, label the verified valve and update household instructions. A new handle alone does not prove full shutoff performance.
One useful question
Can I use pliers on a valve that will not turn?
Do not force it. Extra leverage can break the control or connected piping and create the leak you are trying to prevent. Keep the area accessible and arrange assessment. If water is already escaping, tell the provider that the normal valve is unavailable.