Strapped Plumbing and MSD's 2027 Rules: What St. Louis Building Owners and Builders Need to Know

MSD's 2027 rules require strapped plumbing for basement-level fixtures in every new building in MSD's service area. Strapped plumbing means fixtures below the sewer's safe level drain to a sealed sump, and a pump lifts the wastewater to an overhead line hung from the floor joists, so a sewer backup has no gravity path into the basement. For other permitted work, such as additions and rehabs, the draft allows strapped plumbing, an approved backwater valve, or no protection if the plumbing authority decides protection is impractical. MSD kept the requirement after public comment.

Legacy Plumbing is a union commercial plumbing contractor. We install and service the sump, ejector and overhead piping this rule calls for. Your engineer, the plumbing code official and MSD decide what your project needs.

What the rule says

Section 3.030.09, item 15 ("Protection from Surcharging") of the 2027 draft says MSD requires surcharge protection for basements. Plumbing fixtures lower than the top of the nearest exterior building cleanout (or an approved elevation if there is no cleanout) must be protected from sewage backflow:

MSD's Figures 3-1 and 3-2 show strapped plumbing layouts with a basement sanitary pump. MSD also publishes a separate Strapped Plumbing Requirements document (July 2025) on its checklists page.

The 2018 rules leaned on local plumbing codes and let a backwater valve or strapped plumbing serve, except in combined-sewer and known problem areas where MSD could require strapped plumbing. The 2027 draft drops that paragraph and makes strapped plumbing the rule for all new buildings.

Why MSD made the change

The Home Builders Association commented on the added cost. MSD's October 15, 2026 response said the requirement plans for future conditions rather than relying only on past sewer performance: changing rainfall, including more frequent intense storms, puts more demand on the wastewater system, and the absence of past backups does not remove future risk. MSD acknowledged the added upfront cost and maintenance and said those must be weighed against reduced risk of backups, damage and retrofits. MSD also said rehabs fall under the "other permitted discharges" item, with scope set by the plumbing code having jurisdiction and MSD.

Where else strapped plumbing shows up in the 2027 rules

• Sewer depth. Extendable sanitary mains normally need at least 9 feet of depth. The draft says depths under 9 feet may be considered where all upstream development will have strapped plumbing. MSD cautioned that shallower depths may not be appropriate where existing buildings that stay in place drain to the new sewer.
• Floodplain basements. A basement on a parcel outside the floodplain may sit below the 100-year flood elevation if it has a sanitary pump (strapped plumbing) with the outgoing line above that elevation. Our sister company Kuesel covers the floodplain requirements.
• Levee-protected and high-groundwater areas. The rules say strapped plumbing may be required for buildings in these areas.

What it means for your building

• Design. Basement fixtures route to a sealed, vented sump or receiving tank instead of a gravity line to the building sewer. The pump discharge rises to an overhead line on approved hangers. Size the pump, sump and controls with your engineer.
• Coordination. The overhead line has to meet the building sewer and site lateral at the right elevation, so the plumbing and site utility contractors need to agree on it early. On many projects our sister company Kuesel builds the site sanitary work.
• Power and maintenance. A pump needs power and service. Plan alarm and maintenance access, and put pump service in the building's maintenance plan. See our commercial pump service.
• Existing buildings. Additions and rehabs fall under the "other permitted discharges" item, so a backwater valve may still be an option if the plumbing official approves it.

A short checklist

• Confirm whether your plans are first submitted to MSD before or after January 1, 2027.
• Identify every fixture below the nearest exterior cleanout.
• Show the sump, pump and overhead line on the plumbing drawings.
• Coordinate the line's elevation with the site lateral.
• Plan alarm, power and maintenance access.

Legacy Plumbing handles new construction and tenant finish plumbing across the St. Louis metro. Call 636-978-0120, Monday through Friday, 7:00 AM to 4:00 PM, or see our guide to commercial plumbing permits.

General information from a plumbing contractor, not engineering or legal advice. Your engineer, the plumbing code authority having jurisdiction and MSD set the requirements for your project.

FAQ

What is strapped plumbing?

A setup where basement-level fixtures drain to a pump in an approved watertight sump or receiving tank, and the pump discharges to a plumbing line supported from the floor joists by approved hangers. Because wastewater leaves the basement through an overhead line, a sewer backup has no gravity path in.

Does MSD require strapped plumbing in new buildings?

Under MSD's 2027 draft rules, yes. Basement-level fixtures lower than the nearest exterior building cleanout in all new buildings must be protected by strapped plumbing. MSD kept the requirement after public comment.

Can I use a backwater valve instead?

For new buildings, the 2027 draft requires strapped plumbing. For other sewer discharge locations that need a permit, such as additions and rehabs, the draft allows strapped plumbing, a backwater valve approved by the plumbing code authority, or no protection if that authority finds it impractical.

When do MSD's 2027 rules take effect?

MSD's proposed schedule applies them to plans first submitted on or after January 1, 2027. As of November 9, 2026, MSD still labels the 2027 document a draft.

Sources

• MSD, Rules, Regulations & Design Requirements
• 2027 draft redline (section 3.030.09, item 15; section 3.030.03)
• MSD responses to comments (Oct 15, 2026)
• MSD Required Documents & Checklists (Strapped Plumbing Requirements, July 2025)