Why Won't the Toilet Flush When We Wash Clothes?

Water Pressure

• Most urban households receive their water from the nearest municipal water supply. The water in these systems comes from various sources of groundwater. After receiving treatment for impurities, it is pumped to municipal water storage towers, from where gravity provides the pressure needed to distribute the water to the homes it supplies. Most residential systems use pressure of between 40 and 70 pounds per square inch, or psi. If the water pressure drops below this level, toilets and other water systems may not function correctly.

Water Flow

• Water flow is “the result of your water pressure on the volume of water available for delivery,” according to the FreeDrinkingWater.com. Poor water flow can be the result of damage to the pipes, build up of mineral deposits or corrosion, which will all affect the pressure of the water reaching your home.

Toilet Types

• Residential toilets generally fit into one of two main categories: gravity flow and pressure assisted models. Older homes occasionally have other models, especially in rural areas, but these are rare. Gravity flow toilets are the simplest model and their operation is based on the pressure of the water in the tank, while pressure assisted toilets store air that is released with each flush, forcing the matter in the toilet bowl to dissipate.

Gravity Flow Toilets

• A gravity-flow toilet fills its tank directly from the water source. Depending on its location, the source might need the assistance of a pump to power the movement of the water. The water enters the tank through a fill valve, and passes from the tank to the bowl through a flush valve. If the pressure of the water against the fill valve is insufficient, the tank will not fill. Subsequently, if the pressure of the water in the tank is insufficient, such as when the tank is empty, the toilet will not be able to flush.

Toilet Effects

• If either the water pressure or the water flow is insufficient for any of these reasons, the operation of your washing machine will greatly reduce the quantity of water available for use by other appliances. This can result in your toilet being unable to function correctly, the water in your taps may be unable to run adequately, if at all and your hot water cylinder may be unable to fill to the desired level, which could result in the cylinder overheating and sustaining damage.