There’s a classic scene from an early episode of The Simpsons where Bart torments Homer while he showers by manipulating the hot and cold taps on a faucet. This familiar dynamic is given added hilarity by Homer’s shrill and girlish screams as he suffers under the whim of an unpredictable shower head. Though it’s funny on TV, the reality of a shower that whimsically turns scalding or frigid is hardly hilarious.
But have you ever wondered why shower water reacts so dramatically to a toilet or washing machine? It seems like magic or a sympathetic reaction, but the reality is just simple plumbing, says Mark Smith, the owner of Bath Max, a bathroom remodeling contractor in Chicago who has remodeled over 30,000 bathrooms over the course of his career.
In a normal American home, the shower and other home appliances compete for the same hot water – usually stored in a hot water heater somewhere in the house. If someone turns on a tap or runs the dishwasher while you’re showering, some of the hot or cold water that was flowing in the shower gets diverted, leaving an imbalance of either too much hot or too much cold water. The result? You get burned or frozen.
Fortunately, there are some technologies now on the market to eliminate this nuisance. A mixer valve is a fairly simple and inexpensive piece of equipment that manipulates water pressure to prevent dips or peaks in shower temperature. When a toilet is flushed or faucet run, the mixer valve compensates by decreasing either cold or hot water to maintain the balance and preserve a comfortable temperature. The water pressure is temporarily reduced but will return to normal once the competing demand is shut off.
Another alternative is found in on-demand water heating units, which are smaller localized appliances often installed near the shower head to provide hot water as needed. These heaters may use electricity or gas for energy and ensure that the water is heated to a suitable level before it is sent flowing through the shower head. Since all shower water must pass through this apparatus before flowing into the tub, it is not possible for a toilet, sink, or other appliance to affect the shower temperature. While these on-demand heaters are growing better known, they’re still a budding technology. One thing’s for sure though: Unless you thrive on extreme temperature fluctuations, you’ll be more comfortable with a simple shower modification.