A Quick Map of Your Water Heater
Most residential tank water heaters, gas or electric, follow a similar general layout:
- Cold water inlet — top of the tank, where water enters
- Hot water outlet — top of the tank, where heated water exits to your home
- Thermostat(s) — gas units have one control valve/thermostat near the bottom front of the tank; electric units typically have two thermostats behind access panels on the front side of the tank (upper and lower)
- Gas control valve and pilot assembly (gas units only) — bottom front of the tank
- Pressure relief (T&P) valve — top or upper side of the tank, with a discharge pipe running down toward the floor
- Drain valve — bottom of the tank, usually a hose-bib-style valve
Tankless units are laid out differently — they're wall-mounted with the shutoff valves, drain ports for flushing, and controls all more compact and accessible near the unit itself, rather than spread top-to-bottom like a tank.
Where Is the Pilot Light?
On a gas tank water heater, the pilot light and gas control valve are located in an assembly at the bottom front of the tank, usually behind a small access panel or viewing window. You'll typically see a dial (off/pilot/on), a small window or opening to view the flame, and a reset or igniter button, depending on the model.
If the pilot light has gone out, most gas water heaters have relighting instructions printed directly on the tank, near the control valve. General steps typically involve: turning the gas control to "off," waiting several minutes for gas to clear, switching to "pilot," holding the igniter or reset button while lighting or igniting the pilot, and holding it for the specified time before releasing.
When to call a pro instead: if the pilot won't stay lit after a couple of relight attempts, that's frequently a failing thermocouple (the safety sensor that keeps gas flowing only when the pilot flame is detected) — a fairly common and inexpensive repair, but not a DIY judgment call given it involves a gas safety component. A strong gas smell at any point means stop immediately, don't attempt to relight anything, ventilate the area, and call for service.
Where Is the Thermostat?
- Gas water heaters have a single dial-style thermostat built into the gas control valve at the bottom front of the tank — the same assembly as the pilot light.
- Electric water heaters typically have two thermostats, one behind an access panel near the top of the tank and one behind an access panel near the bottom, each controlling one of the two heating elements. These panels usually need a screwdriver to open, and there's often an insulation flap underneath.
Safety note: the recommended setting for most households is 120°F. Higher settings increase scald risk and accelerate mineral scale buildup and energy use; much lower settings can allow bacteria growth in stored water. If you're adjusting an electric thermostat, the power to the unit should be shut off first — this is a reasonable point where many homeowners choose to call a professional rather than work near live electrical connections inside the tank's control cavity.
Where Is the Water Heater Shutoff Valve?
There are two shutoffs that matter, and they do different things:
- Cold water inlet valve — located on the cold water supply pipe entering the top of the tank, usually a lever-style ball valve or a round gate valve. Closing this stops water from flowing into the tank, which is what you'd do before any work on the unit itself.
- Gas shutoff valve (gas units) — located on the gas supply line leading to the water heater, typically a lever-style valve you turn a quarter-turn to shut off gas flow, separate from the pilot's internal control valve.
Knowing where both of these are before you need them, rather than during an active leak, is one of the simplest things a homeowner can do to limit damage in an emergency.
Where Is the Drain Valve?
The drain valve is located at the bottom of the tank, typically a hose-bib-style spigot you can attach a standard garden hose to. This is the valve used for flushing sediment out of the tank.
Should You Flush Your Water Heater Yourself?
This is genuinely a task some homeowners handle themselves, and others reasonably prefer to leave to a professional — it's less about difficulty and more about comfort working around hot water, pressure, and (for gas units) the pilot light.
General steps for a DIY flush:
1. Turn off power to the unit — switch the gas control to "pilot" (don't fully extinguish it) on gas units, or shut off the breaker on electric units.
2. Shut off the cold water inlet valve so no new water enters the tank.
3. Connect a garden hose to the drain valve and run the other end to a floor drain or outside.
4. Open the drain valve and a hot water fixture elsewhere in the house to let air into the tank so it drains properly.
5. Let the tank drain fully, then briefly open the cold water inlet valve to stir up remaining sediment and flush it out, repeating until the water runs clear.
6. Close the drain valve, refill the tank fully (open a hot water fixture until water runs steadily to confirm it's full and purge air), then restore gas/power settings.
Where DIY has real limits: if your drain valve is corroded or won't fully close again after opening it, if you're not confident relighting a gas pilot afterward, or if the tank is old enough that you're worried disturbing built-up sediment could reveal an underlying leak, those are good reasons to have a plumber handle it. A flush on a tank that's already near the end of its life can sometimes expose a leak that was being partially masked by sediment — not a reason to avoid flushing altogether, but a reason to know what you're getting into on an older unit.
When to Just Call Us
- Pilot light won't stay lit after a couple of relight attempts
- Any gas smell near the unit
- Drain valve won't close or is leaking after a flush
- Inconsistent hot water, rumbling noises, or visible rust/corrosion — signs worth a professional look regardless of whether you're comfortable with basic maintenance
- You're just not comfortable working around the gas or electrical components, which is a completely reasonable line to draw
Not comfortable tackling it yourself, or dealing with a water heater issue beyond basic maintenance? Call American Rooter & Drain at (208) 366-5771 or book online to schedule a visit. We serve Boise, Meridian, Nampa, Caldwell, and communities throughout the Treasure Valley and Eastern Oregon.
Learn more about our water heater repair, replacement, and installation services.
Frequently asked questions
Where is the water heater pilot light located?
On a gas water heater, the pilot light and gas control valve are located at the bottom front of the tank, usually behind a small access panel with a viewing window and a dial for off/pilot/on settings.
Where is the water heater thermostat located?
Gas water heaters have a single thermostat built into the gas control valve at the bottom front of the tank. Electric water heaters typically have two thermostats behind access panels — one near the top and one near the bottom of the tank — each controlling a separate heating element.
Where is the water heater shutoff valve?
The cold water inlet shutoff valve is located on the cold water supply pipe entering the top of the tank. Gas units also have a separate gas shutoff valve on the gas supply line leading to the unit, distinct from the pilot's internal control valve.
Where is the water heater drain valve?
The drain valve is at the bottom of the tank, typically a hose-bib-style spigot designed to connect a standard garden hose for draining and flushing sediment.
How do I flush my water heater myself?
Turn off power or switch a gas unit to pilot mode, shut off the cold water inlet valve, connect a hose to the drain valve, open the drain valve along with a hot water fixture elsewhere in the house to let air in, drain the tank fully, briefly reopen the inlet valve to flush remaining sediment, then close the drain valve and refill the tank before restoring power or gas settings. If the drain valve won't close afterward or you're not comfortable with any step, it's reasonable to call a plumber instead.
