2026-02-02 – Weekly Plumbing News : Who invented the P-trap?

Last week on the forum, discussions centered around practical solutions and historical trivia in plumbing. Members delved into the best approaches for dealing with a bellied drain, debated the water-saving efficiency of faucets versus toilets, and shared tips for reducing energy waste in water heaters. An unexpected historical discussion about the inventor of the P-trap also sparked curiosity, alongside practical exchanges about energy-efficient pump use and strategic water heater replacements. Additionally, members explored the importance of forming solid work site relationships and how continuing education can enhance inspection outcomes.


This Week’s Hot Topics

Bellied 4-inch drain: fix or maintain
In this thread, members weigh the pros and cons of repairing versus maintaining a bellied drain. It’s a practical debate that could save you time and effort on future projects.
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Bigger water saver: faucets or toilets
This discussion questions which fixtures contribute more to water conservation. It’s a good chance to reassess assumptions about household water savings.
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Quick checks for water heater energy waste
A thread with handy tips for identifying energy inefficiencies in water heaters. Perfect for those looking to optimize home energy use.
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Who actually invented the P-trap
A historical dive into the origins of the P-trap has members fascinated. It’s a light-hearted yet informative look into plumbing history.
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Cutting pump energy without losing pressure
This conversation focuses on balancing energy efficiency with performance in pump systems. Ideal for those looking to reduce operational costs.
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Before you replace that water heater
Members discuss key considerations before committing to a new water heater, offering valuable pre-purchase insights.
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Finding allies on the job site
A practical exploration of building supportive work relationships. It’s a useful read for improving job site dynamics.
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CE that improves inspection outcomes
This thread covers how continuing education can directly enhance inspection results, a must-read for those committed to professional development.
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That’s all for this week’s digest. Looking forward to seeing more of your valuable contributions in the discussions ahead.

On the ‘bellied drain’ threads, I mark my camera pushrod every 5 ft with a wax pencil and run a full-bore flush; if water lingers in the low spot longer than about 10 seconds, I price a spot dig instead of lining because liners won’t fix a belly. Anyone timing it differently in cast vs PVC? Side note on the P‑trap bit: Cumming’s 1775 S‑trap patent is the upstream ancestor, but out in the field it still comes down to a tight seal and proper venting.

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@Guide Pretty sure Alexander Cumming (1775) invented it; see Trap (plumbing) - Wikipedia; if you’ve got S-traps, retrofit to vented P-traps.

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It’s interesting how many people overlook the importance of venting in plumbing… The P-trap’s design is great for preventing sewer gases, but it’s crucial to ensure proper venting to maintain its function. I’ve seen some systems back up just because of bad airflow.

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