---
title: "Water wash (recovery boiler)"
description: "A water wash on a recovery boiler is the offline cleaning campaign performed during a full boiler shutdown, using high-pressure water lances to remove consolidated deposits from superheater, generating-bank and economiser tubes that in-service sonic horns and chill-and-blow could not remove."
canonical_url: "https://sylio.co/glossary/water-wash-recovery-boiler"
last_updated: "2026-06-28T02:29:36.576Z"
---

A **water wash** on a [recovery boiler](/glossary/recovery-boiler) is the offline cleaning campaign performed during a full boiler shutdown, using high-pressure water lances to remove consolidated deposits from [superheater](/glossary/superheater), [generating-bank](/glossary/generating-bank) and [economiser](/glossary/economiser) tubes that in-service [sonic horns](/glossary/sonic-horn) and [chill-and-blow](/glossary/chill-and-blow) could not remove.

## Frequency

Mills target intervals of 18–36 months between water-wash campaigns, depending on:

- Boiler design and age
- Black-liquor solids loading
- Effectiveness of continuous cleaning (sonic horns, [IK sootblowers](/glossary/ik-long-retract-sootblower))
- BLRBAC inspection programme

## Cost of a water wash

A water-wash campaign typically takes 5–10 days of full boiler shutdown — multi-million-dollar lost production — plus the labour and consumables of the cleaning itself. Every additional month between water-washes is therefore worth substantial money to the mill operator.

## How sonic horns extend the water-wash interval

Continuous [sonic-horn](/glossary/sonic-horn) cleaning during operation prevents the deepest, hardest deposits from forming. Plants commonly report water-wash interval extension from 18 months to 24+ months after retrofitting horns to a previously sootblower-only recovery boiler.

## Related terms

- [Recovery boiler](/glossary/recovery-boiler)
- [Chill-and-blow](/glossary/chill-and-blow)
- [Superheater](/glossary/superheater)
- [Sonic horn](/glossary/sonic-horn)