What is ice pigging?

A no-dig, no-chemical pipe cleaning technology that pumps a dense, soft ice slurry through your network — scouring biofilm, scale and sediment out in a single, controlled pass.

Ice pigging is the process of using pumpable ice as a soft, conformable pig to clean the inside of a pipeline.

Instead of a solid foam or polyurethane pig — which can get stuck, damage fittings, or skip past bends — ice pigging uses a thick slurry of crushed ice mixed with a freezing-point depressant. The slurry behaves like a liquid when it needs to (going around bends, through valves, past instrumentation) and behaves like a solid when it counts (scouring the pipe wall).

Originally developed at the University of Bristol, ice pigging is now used on potable water mains, sewer rising mains, food and beverage process lines, district heating circuits, and industrial pipework worldwide.

Why a slurry beats a solid pig — every time.

The cleaning performance comes from a few specific properties of an ice/brine mixture that no other cleaning method has all at once.

Two-phase fluid

Roughly 60–80% solid ice crystals suspended in chilled brine. The crystals do the scouring; the brine carries them through bends and fittings.

Shear at the wall

Where the slurry meets the pipe wall, ice particles generate high local shear — enough to dislodge biofilm and loose scale, but never enough to damage the pipe.

Self-clearing

If the slurry encounters a partial blockage or valve restriction, it simply melts — there is no risk of a stuck pig. The system stays controllable from end to end.

Concentrated waste

All the dislodged material exits in a small, concentrated discharge slug — typically a fraction of the volume that traditional flushing would produce.

From survey to sign-off in a single shift.

A typical ice pigging operation runs end-to-end in 4–8 hours, with the pipe back in service the same day.

01

Survey & isolate

We map the section to be cleaned, identify a suitable injection point (typically a hydrant or tapping) and a discharge point, and isolate the run.

02

Produce the slurry

Ice is made on site (or delivered) and blended with a food-grade freezing-point depressant in our mobile rig until it reaches the right consistency.

03

Inject the pig

A measured slug of slurry — typically equal to 1–2× the pipe volume — is pumped in under controlled pressure behind a water push.

04

Scour & discharge

The slurry travels at line velocity, lifting biofilm and sediment off the wall. The dirty slug discharges through a hydrant or flush point into a tanker or to drain.

05

Verify & return to service

Turbidity, free chlorine, conductivity and bacteriology are sampled before the asset is signed back into service.

Six things ice pigging does that nothing else does.

Can't get stuck

If anything goes wrong, the slurry melts. Period.

No excavation

Inject and discharge from existing hydrants, valves or taps.

1/20th the water

A short, dense slug replaces hours of flushing.

No chemicals

Just water, ice and a food-grade salt. Discharges to standard drainage.

Hours, not days

Most assets are back online the same shift.

Measurable result

Turbidity in the discharge slug proves how much was removed.

Where ice pigging fits in the cleaning toolkit.

Safe for potable assets

Food-grade sodium chloride is the only additive — same salt used in food production.
Discharge meets standard trade-effluent and drinking-water consents in most jurisdictions.
No confined-space entry, no excavation, no road closures for typical jobs.
Asset remains pressurised — no need to fully drain and recommission.

Built for sustainability targets

From university lab to global utility standard.

Early 2000s

Researchers at the University of Bristol’s Department of Mechanical Engineering investigate two-phase ice slurries for pipeline cleaning.

2010

First commercial deployments on UK water mains demonstrate a step- change reduction in flushing volumes and turbidity.

2015–2020

Adoption spreads across Europe, North America and Australasia for food and beverage changeovers and district heating networks.

Today

Ice pigging is specified by major water utilities, food manufacturers, refineries and energy operators worldwide — including the network PolarFlow operates.

Common questions, answered.

Is ice pigging safe for drinking water mains?

Yes. The only additive is food-grade sodium chloride, and the process meets potable water standards in the UK, EU, US and Australasia. Networks are returned to service after standard bacteriological clearance.

Could the ice get stuck in a pipe?

No. Unlike a solid foam or polyurethane pig, an ice slurry simply melts if it encounters a restriction or loses motion. There is no scenario where it can become a permanent obstruction.

What pipe sizes and materials does it work on?

PolarFlow regularly cleans pipes from 50 mm to 1,500 mm in diameter, in cast iron, ductile iron, steel, stainless steel, PE, PVC, AC and lined pipe. Bends, tees and inline instruments are not a problem.

How long does the asset need to be offline?

Most jobs are completed in 4–8 hours including isolation, cleaning and sampling. For redundant mains, customers often experience no service interruption at all.

What does the discharge look like?

A short, highly concentrated slug of dirty water containing the biofilm and sediment removed from the pipe. It is typically tankered away or discharged under standard trade-effluent consent.

How is it different from traditional pigging?

Traditional pigging pushes a solid object through the pipe — which can get stuck, damage fittings, or bypass internal features. Ice pigging is a fluid that scours like a solid but flows like a liquid, so it cleans more thoroughly with none of the risk.

Have a more specific question about your asset? Send us a pipe schedule and we’ll give you a feasibility answer within 24 hours.

See ice pigging on your own pipework.

Book a no-obligation site walk and feasibility review. We’ll model the cleaning effect for one of your worst-performing sections.