Tap water in the AdBlue tank
Tap water in the AdBlue tank is worse than demineralised water because of what is dissolved in it. Calcium, magnesium and chloride leave deposits in the dosing injector and the heated lines. Call 01293 248666 for a drain and flush.
ISO 22241 specifies demineralised water specifically to keep the metal and mineral content down to parts per million. UK mains water is well above that almost everywhere, and hard-water areas are far above it. Those minerals do not evaporate in the dosing injector — they deposit. The injector tip runs hot and sprays a fine mist, and mineral scale at that tip is a classic blocked-injector cause. Chloride adds a corrosion risk to the stainless internals.
Call 01293 248666 From just £89 call-out fee
Tap water in the AdBlue tank — the severity verdict
| Severity | Likely recoverable Usually resolved by a drain and flush, with a fluid-quality check afterwards. |
|---|---|
| What went where | Tap water in the AdBlue tank |
| Direction | Into the AdBlue tank |
| Typical cost | £190–£420 typical total, from a £89 call-out |
| Time on site | About 70 minutes |
| Call-out | From just £89 call-out fee |
| Helpline | 01293 248666, 24 hours |
£89 is the call-out. An AdBlue tank drain and flush is quoted on the phone before a technician travels. If the SCR system needs component replacement — dosing injector, pump, tank or catalyst — that is separate, and you will be told before any work starts. If this is a job we cannot fix at the roadside, we will tell you that on the phone rather than after we arrive.
What to do right now
- Do not run the system any longer than you must.
- Note whether you are in a hard water area — it affects how thorough the flush needs to be.
- Call 01293 248666.
What a technician actually does
Drain, demineralised water flush, AUS 32 flush, dosing injector inspection for mineral deposits, refill and code clearing. Where the injector is already scaled, replacement is quoted separately.
Why this is not the same job as the other direction
This is contamination of the SCR dosing circuit — tank, metering pump, heated lines, dosing injector and potentially the catalyst. It is not the fuel system, and it is not the cheaper job. Anyone quoting a flat drain price for this has not looked at the system.
Common questions
Is tap water really different from demineralised?
For this system, yes. ISO 22241 caps metal content at parts-per-million levels precisely because the dosing injector deposits whatever the water carries.
I only put a little in. Does that matter?
It matters less, but the deposits it leaves are at the injector tip either way. It is a drain and flush, and the injector gets looked at.
Does hard water make this worse?
Yes. More dissolved mineral means more deposit, and the injector is the component that pays for it.
What customers say
4.8 out of 5 from 2,190 Trustpilot reviews. What reviewers mention most is that the technician stayed calm and professional with a driver who was embarrassed and stressed, and that somebody arrived when they said they would.
The most common criticism is price. People do not expect a wrong-fluid job to cost what it costs, and that is a fair complaint to publish rather than bury. The answer is the From just £89 call-out fee, a quote given on the phone before a technician travels, and being told when a job cannot be done at the roadside rather than after somebody has arrived and charged for the visit.
Related AdBlue problems
Start from a symptom instead
Where we cover
Who you are dealing with
Work booked through AdBlue in Fuel is carried out by Fuel Fixer Ltd, company no 08520551, registered at Fairway House, Portland Road, East Grinstead, RH19 4ET, trading as Forecourt Assist and part of Fuel Fixer International, which is owned by Stockbridge Capital Holdings.
Reference: ISO 22241 — the AdBlue standard.
Across the Fuel Fixer network
Every brand above belongs to Fuel Fixer International, owned by Stockbridge Capital Holdings. The directory lives on the operator's own site: forecourtassist.co.uk/network.