Quick Answer:
If your outdoor spigot drops pressure when two hoses run, it usually means the house supply or the splitter can’t deliver enough flow to both hoses. Start by running a single hose and note the change in pressure, then test the splitter to see if it restricts flow. Simple checks often reveal whether the problem is a weak supply, a clogged fitting, or a poor splitter.
Why This Happens
- Shared supply limits: A single spigot and the home’s supply pipe can only deliver so much water. Two hoses can exceed that capacity and reduce pressure at each outlet.
- Splitter or fitting restriction: Cheap or clogged splitters have narrow passages that reduce flow when both outlets are used.
- Partially closed valve or pressure regulator: The shutoff by the spigot or a pressure regulator may be partly closed, limiting flow to multiple lines.
- Internal plumbing issues: Corrosion, buildup, or a failing backflow device can reduce available water.
Step-by-Step What to Do
Step 1 — Run a single hose and observe
- Attach one hose to the spigot and open it fully. Note how strong the stream is from the hose end or feel the pressure at the nozzle.
- Run only this hose for 30–60 seconds to let flow stabilize. Record whether the flow is high, moderate, or weak.
Step 2 — Add the second hose and note pressure change
- Attach the second hose and open it fully. Compare the flow on each hose to the single-hose result.
- If both drop noticeably, you have a supply or splitter capacity issue. If only one drops, check that hose for kinks, clogs, or a blocked nozzle.
Step 3 — Test splitter restriction
- Remove any splitter or adapter and connect hoses directly (or try a different, higher-quality splitter). If flow improves with a different splitter or with just one hose on the spigot, the original splitter is the restriction.
- Inspect the splitter for sediment, mineral buildup, or internal valves that might be partially closed.
Step 4 — Check house-side supply and valves
- Verify the outdoor shutoff valve (if present) is fully open. Check any nearby pressure regulator or isolation valve.
- Test indoor taps: if several indoor fixtures also have low pressure, the problem is likely upstream (main supply, regulator, or utility service).
Step 5 — Look for leaks and other causes
- Inspect visible piping for leaks or corrosion. A leak can reduce pressure when demand increases.
- Check hoses for kinks or internal blockage. Try swapping hoses to rule out a bad hose or nozzle.
What Not to Do
- Do not run multiple hoses without testing splitter. This can hide the real restriction and cause frustration.
- Do not force plumbing parts that are stuck—forcing can break fittings and create larger problems.
- Do not attempt to modify or remove a pressure regulator or main shutoff unless you are confident and the water is turned off at the correct isolation point.
When to Call a Professional
- Persistent low pressure at multiple fixtures after your tests suggests a supply or regulator problem best handled by a plumber.
- Visible leaks, rusty fittings, or a spigot that bangs loudly could indicate failing components; in that case, call a pro.
- If you suspect the spigot or piping backs water into house or causes contamination, stop using it and get professional help promptly.
- If you hear a loud or repeated hammering noise when valves open or close, have a plumber inspect the system—this can indicate water hammer or a failing valve.
Safety Notes
- Turn off the appropriate isolation valve before disassembling any spigot or fittings. If you’re unsure which valve controls the outdoor spigot, shut off the main water to the house before working.
- Do not use excessive force on old or corroded fittings—use proper tools and consider replacement rather than risky removal.
- Avoid electrical tools near wet areas and wear gloves and eye protection when working on pipes.
Common Homeowner Questions
- Why does pressure drop only when both hoses are on?
Because the combined demand exceeds the available flow from the spigot, splitter, or supply line. - Can a cheap splitter cause this problem?
Yes — narrow internal passages or valves in low-quality splitters often reduce flow when both outlets are used. - Will replacing the hose help?
Sometimes—if a hose is kinked or clogged it can limit flow, but if the supply or splitter is the bottleneck, a new hose won’t fix it.