How to flush a common weater heater

1. Connect drain hose
2. Turn thermostat down
3. Turn gas valve to off position and turn off main gas line
4. Shut cold water valve off above water heater - turn clockwise
5. Open hot water faucet inside- should run dry
6. Open drain valve (counter clockwise) and let all water drain. While draining, open pressure relief valve to horizontal position. Takes 55 minutes (about 10 blue buckets) to empty.
7. Once empty, turn cold water valve on for 30 seconds at a time and allow to drain. Repeat until reasonably clear.
8. Close drain valve and turn cold water valve on to let tank refill. Once water comes out of faucet inside, turn it off, and reset pressure relief valve.
9. Turn control knob to pilot
10. Turn on main gas supply
11. Hold down control knob and press lighter until click then release. Hold knob for a minute. After releasing it should pop up. Pilot should remain on.  Note: pilot light is at back of unit - awkward to see.
12. Replace outer cover and turn knob to on.
13. Return thermostat to normal value.