This is known as water hammer. The air chambers in the walls have leaked out the air and filled with water. To correct this follow these steps. First, turn off the water to your house using the valve outside your house or at the water meter. Next, turn on every faucet in the house, including outside hose bibbs and shower valves. After they have been drained, get a shallow pan and disconnect the toilet supply lines, allowing the water to drain into the pan. This will ensure that as much water as possible has been drained from your water pipes in the walls. Next, put that toilet valves back together and turn all of the faucets you previously turned on, off. Turn the water back on to the house. Wait 10-15 minutes before turning a valve on. This procedure will recharge the air chambers and eliminate the water hammer.