Mixer showers have difficulty controlling water temperature. When the toilet is flushed somewhere in the house, or a cold faucet is switched on, the cold-water supply is suddenly reduced. This means that a higher proportion of hot water is coming through the shower. The opposite is the case when someone turns on the hot faucet, causing the water from the shower to be freezing cold. This can be remedied with mixer showers that are plumbed into the wall and use built-in thermostats. These constantly regulate the temperature of the mixed water to ensure adequate temperature.