I had my hot water re-plumbed due to the copper lines corroding. After everything was done the hot water was discolored. At this point I thought it would be a good idea to flush the tank. I have a traditional 40 gallon tank running on natural gas. I hooked up the garden hose to the plastic drain and opened the valve. All I got was a little trickle of water. I opened the faucet closest to the tank with no change. Normal flow of water out of the faucet. I tried various combinations of having the faucet on/off, cold supply on/off and hot valve on/off. The drain valve is all the way open but the best I could get was 2-3 cups of hot water. What am I doing wrong? Am I missing some step? I get normal water flow from all faucets in the house. After a week of normal use the color has gone away but I would still like to know what I am doing wrong.