Pressure Drops When Multiple Fixtures Run

This hub covers pressure drops that only happen when multiple fixtures run at the same time. Common examples include showers that weaken when a toilet flushes, sinks that drop when the washer fills, or pressure that collapses when irrigation starts.

These issues are often about total demand, shared piping, or a restriction that only shows up under higher flow; they can also appear as temperature swings when pressure changes. Use the groups below to find the scenario closest to yours and open the matching article.

See the parent category: Water Pressure Behavior & Regulation

Fixture-to-fixture interference

Problems where one household fixture noticeably affects another when it runs.

• Shower pressure drops when toilet flushes

  Explains why a toilet flush can cause a temporary shower flow drop and what to check first.

• Kitchen sink loses pressure when washer runs

  Describes how washer fill cycles can reduce sink flow and where shared supply issues often occur.

• Pressure drops when dishwasher fills

  Covers typical causes of low flow at nearby fixtures while a dishwasher is drawing water.

• Pressure drops when ice maker cycles

  Focuses on intermittent drops linked to fridge ice maker fills and the plumbing points to inspect.

• Pressure loss when upstairs fixtures used

  Looks at why using upstairs plumbing can reduce pressure elsewhere, including piping and valve considerations.

High-demand draws (hose, tub, laundry, pool)

Scenarios where large-volume uses create noticeable pressure reductions.

• Pressure weakens when hose is used

  Discusses how outdoor hose use can lower indoor fixture pressure and common supply limitations.

• Pressure loss when laundry starts

  Notes how washer fill demand can affect other taps and where flow restrictions are likely.

• Pressure collapse when bathtub fills

  Explores why filling a tub may cause broader pressure drops and what to consider about shared piping.

• Pressure loss when pool autofill runs

  Summarizes the impact of pool autofill devices on household pressure and typical mitigation points.

Irrigation and sprinkler zone effects

Pressure changes tied to irrigation systems starting or zones switching.

• Pressure collapse when irrigation starts

  Describes how irrigation demand can drop household pressure and what to check on the supply side.

• Pressure unstable when sprinkler zone starts

  Looks at pressure swings when zones cycle and common causes like zone sequencing or line size.

Multiple fixtures and hot-water impacts

Issues that combine high demand with hot-water delivery or temperature changes.

• Two showers running causes cold water loss

  Explains why simultaneous showers can lead to loss of cold water and balancing issues in the system.

• Hot water disappears when multiple taps open

  Describes how multiple hot-water draws can exhaust supply or affect mixing at faucets.

• Pressure fine until second fixture opens

  Notes situations where pressure holds with one fixture but drops as a second is opened, often due to shared piping limits.

• Pressure only weak when demand is high

  General overview of pressure issues that appear only under high simultaneous demand and where they originate.

• Water temperature changes with pressure drop

  Discusses how pressure shifts can alter mixed water temperature and what factors contribute to the change.

Peak hours and refill-related drops

Patterns tied to municipal peaks or equipment that periodically refills.

• Pressure drops during peak city hours

  Outlines how municipal demand cycles can reduce local pressure and how to recognize the pattern.

• Pressure weakens when water heater refills

  Explains transient pressure changes tied to water heater refill cycles and where they appear in the home.

All Articles in This Cluster

• Shower pressure drops when toilet flushes
• Kitchen sink loses pressure when washer runs
• Pressure drops when dishwasher fills
• Pressure drops when ice maker cycles
• Pressure loss when upstairs fixtures used
• Pressure weakens when hose is used
• Pressure loss when laundry starts
• Pressure collapse when bathtub fills
• Pressure loss when pool autofill runs
• Pressure collapse when irrigation starts
• Pressure unstable when sprinkler zone starts
• Two showers running causes cold water loss
• Hot water disappears when multiple taps open
• Pressure fine until second fixture opens
• Pressure only weak when demand is high
• Water temperature changes with pressure drop
• Pressure drops during peak city hours
• Pressure weakens when water heater refills