---
title: "Pumped Sewage & Pressure Mains"
canonical: https://www.alompoly.com/applications/pressure-sewerage
source: ALOM Poly Extrusions Limited
---
# Pumped Sewage & Pressure Mains

Fully fused rising mains for pumping stations and low-lying zones.

## Overview
Sewage rising mains from pumping stations and lift stations to the nearest gravity chamber or treatment works, used where the terrain is flat, the water table is high, or a gravity gradient cannot be achieved across the catchment.

## Specification
- **Product range:** QFlow Solid-Wall HDPE
- **Standard:** IS 4984
- **Rising Main Sizes:** 90 mm to 315 mm OD
- **Pressure Class:** PN 10 / PN 16 rating
- **Standard Code:** IS 4984 / ISO 4427

## Why HDPE here
- Fully welded line with no gasket for septic sewage to attack
- Elastic wall absorbs the surge every pump start and stop puts into the main
- Smooth bore holds its friction loss, so the pump duty point does not drift

## Typical deployments
- Sewage pumping station rising mains
- Lift station discharge lines
- Low-lying zone pressure sewerage
- STP inlet transfer mains

## Specification and site notes

### Size for surge, not for steady flow
The governing load on a sewage rising main is the transient every time the pump starts or stops, not the running pressure. Do the surge analysis, then choose PN. PN 10 covers short lift-station mains; longer transfers and high static lifts need PN 16.

### Septicity and the joint
Sewage goes septic in a rising main, and the H₂S that generates attacks elastomers and cementitious materials. A butt-fused HDPE line has neither, so the joint is not the weak point it is in a gasketed pressure main.

### Air valves at every high point
Air pockets at summits throttle the main and amplify surge. Fit air release valves at each high point and washouts at each low point, and record them, because a rising main that has never been scoured will eventually block at the low point.

### Do not oversize: hold the self-cleansing velocity
A rising main needs a scouring velocity, typically around 0.7 to 1.0 m/s at least once a day, to move solids. Choosing a larger diameter to reduce friction can drop velocity below that and silt the main up, which is the commonest design mistake on these lines.

## FAQ

### When is a pressure sewer used instead of a gravity sewer?
Where the terrain is too flat to hold a gravity gradient across the catchment, where the water table makes deep gravity excavation impractical, or where a low-lying pocket has to be lifted into a higher network. Otherwise gravity is always cheaper to run.

### What pressure class does a sewage rising main need?
It is set by the surge, not the running pressure. Do the transient analysis first: PN 10 covers short lift-station mains, while longer transfers and high static lifts need PN 16.

### Does septic sewage damage an HDPE rising main?
No. Septicity generates H₂S, which attacks elastomeric seals and cementitious linings. A butt-fused HDPE main has neither a gasket nor a lining, so the usual failure point is absent.

### Can a rising main be too large?
Yes, and it is a common error. Oversizing to cut friction drops the velocity below the roughly 0.7 to 1.0 m/s needed to move solids, and the main silts up. Size for a self-cleansing velocity at least once daily.

## Commonly specified sizes
- [QFlow 110mm Solid Wall HDPE Pressure Pipe](/products/size/110mm-hdpe-pipe)
- [QFlow 160mm Solid Wall HDPE Pressure Pipe](/products/size/160mm-hdpe-pipe)
- [QFlow 225mm Solid Wall HDPE Pressure Pipe](/products/size/225mm-hdpe-pipe)
- [QFlow 315mm Solid Wall HDPE Pressure Pipe](/products/size/315mm-hdpe-pipe)

## Related applications
- [Municipal Sewerage](/applications/municipal-sewerage)
- [Water Supply Networks](/applications/water-supply)
- [Sewer Rehabilitation & Renewal](/applications/sewer-rehabilitation)
- [Industrial Fluid Transfer](/applications/industrial-fluid-transfer)

## See also
- [QFlow Solid-Wall HDPE product range](/products/qflow)
- [All industries and sectors served](/industries)
- [Reference projects](/projects)
- [HDPE pipe dimensions and size chart](/resources/hdpe-pipe-dimensions)

For CAD drawings, compliance certificates and B2B pricing estimates, contact mktg@alom.in.