Are you talking about the drains for the packing glands? If they are discharging more water than a ¾” pipe can flow, they probably need to be adjusted or repacked.
-Kyle M at Aero From: [email protected] <[email protected]> Sent: Monday, February 23, 2026 7:01 AM To: [email protected] Subject: [External][Sprinklerforum] Re: Inlet to manifold size We have four fire pumps with 3/4” drain lines each. Each drain line (not sure terminology) is constantly discharging water (even in churn), there are four 3/4” lines leading to a 3/4” connective manifold header that then drains into a floor drain. Google says “Connecting four 3/4" drain lines into a single 3/4" manifold is generally not allowed by plumbing codes for standard, high-volume, or gravity-based drain systems, as it will likely result in insufficient drainage and backflow.”
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