How to clean Windshield Washer Fluid Reservoir?

[thedriver]

I've got a B7 Passat and recently had a clogged washer jet. Mine are heated so it wasn't a cheap replacement.
Initially I was trying to clean it and noticed the windshield washer fluid reservoir actually had a lot of black gunk stuck to the sides of the reservoir.

Any thoughts on how to clean it?

I can't see anyway to easily remove the reservoir, it looks like hours of work. I tried vinegar and water but it hasn't made any difference. I thought maybe using CLR or something similar and then pumping it through without the jets attached.

Anyone else successfully cleaner their water reservoir?

[Ozsko]

Just a guess, bicarb soda? I would make sure nothing went on the paint work.

[Transporter]

I’d put the garden hose connected to the hot water in and let it overflow/flush for 1/2hour.
If that wouldn’t help then I’d be removing it.

[Amalgam]

Hi,

The black gunk is known as biofilm and is a growth of bacteria/mold in stagnant water that hasn't been treated.

1/ empty or flush out the reservoir of old washer fluid until only fresh water remains.
2/ add Miltons (available at Coles/Woolies baby section. Used to disinfect baby's bottles) to make up a 5% solution and leave until the biofilm is destroyed. 1 hr - overnight.
3/ flush the reservoir out with fresh water
4/ add washer additive to prevent biofilm build up.

BEWARE MILTONS IS A MILD BLEACH

Good luck

[ope126]

Hi,

The black gunk is known as biofilm and is a growth of bacteria/mold in stagnant water that hasn't been treated.

1/ empty or flush out the reservoir of old washer fluid until only fresh water remains.
2/ add Miltons (available at Coles/Woolies baby section. Used to disinfect baby's bottles) to make up a 5% solution and leave until the biofilm is destroyed. 1 hr - overnight.
3/ flush the reservoir out with fresh water
4/ add washer additive to prevent biofilm build up.

BEWARE MILTONS IS A MILD BLEACH

Good luck

Nice write up mate!!!

[thedriver]

Awesome - thanks.

I spoke with someone at VW today and I was given a price of about two hours labour and ~$140 for a new reservoir. It's probably cheaper to replace it if your pulling it out than spend time to try and clean it.
I also spoke with a mechanic that had experience with these in Mercedes and he said they sometimes used an ultrasonic cleaner... interesting idea.

I'll try the Miltons and the hot water and report back - thanks.

[ian]

Like all mold it is easily treated with Bleach , Fill the reservoir with clean water add a full cup of bleach ,within 24 hours the mold will of disappeared, Flush and refill

[Amalgam]

I'll try the Miltons and the hot water and report back - thanks.

Just use room temp water as hot water will accelerate the decomposition of the Miltons.

George

[thedriver]

sorry, I meant I'd use them both separately. Thanks for clarifying though.

[thedriver]

TLDR: For removal of biofilms, my current research suggests using Chlorine Dioxide, not anything else listed in this thread so far.

The black gunk is known as biofilm and is a growth of bacteria/mold in stagnant water that hasn't been treated.
2/ add Miltons (available at Coles/Woolies baby section... make up a 5% solution and leave until the biofilm is destroyed. 1 hr - overnight

So I've had some success (I think) cleaning out the washer fluid bottle, but it's hard to be sure because I can't easily access it to check. And, after some further research it turns out that Miltons may not be the right choice, which is kind of what I experienced as well.

I called Miltons first and asked them about their product, but they had no idea, the person was clueless. The person wasn't technical at all and didn't seem to understand that killing bacteria is not the same as dissolving it into the solution (e.g. physical removal of it from the walls).

Anyway, I used the Miltons at Amalgams recommended rate of 5% (maybe even a little stronger) and let it sit for about 6 hours.
I had to pump out the water first, so I removed the spray nozzles from the tubes and popped the tubes onto the edge of the bonnet so the would pump straight up into the air when the bonnet was closed. This way I could close the bonnet to allow the pump to activate and at the same time spray extra water onto the bonnet so the solution was further diluted as it hit the car.

After fully emptying the reservoir (about 3-4 mins of constant on off ), I checked the washer fluid bottle and could see the biofilm hadn't been removed. It was still there, it had just been bleached. Maybe some if had been removed, but it was impossible to tell and there was obviously still a lot of it.

I sprayed water into it using the Jet setting on my hose nozzle and that disrupted it, more so than before using the Miltons, so the Miltons at least seemed to make it easier to remove. After filling the bottle and pumping it out again I could see bits of stuff coming out through the tubes.
I repeated this flushing about 6 or seven times (partly because I was going to add another chemical and didn't want their to be any reaction).

Seeing how much biofilm was still attached to the bottle after using the Miltons, I didn't feel like I could trust that it was clean in the main part of the bottle where I couldn't see. So I thought I'd try some CLR. I called them and they said absolutely I could use it, but use it at half the ratio that is suggested on the bottle first. If that didn't work, try it at the recommended ratio (1:1).

I tried the CLR and more crap came out, but I still couldn't be sure it was actually clean at the main part of the reservoir. Again I flushed it probably 5 or 6 times to be sure I wasn't spraying any CLR onto my car later.

I found this link last night about Biofilms though: Biofilm removal and control - Lenntech
Interestingly, they note that hypochlorite has little effect on biofilms... And guess what the Miltons is made of?
The Miltons Liquid Solution is Sodium Hypochlorite (the Miltons Tablets are Sodium Dichloroisocyanurate).
So I'm assuming that's why I didn't see any actual removal effect of the biofilm using the Miltons.

That link notes that "it has been proven beyond doubt that chlorine dioxide removes biofilm from water systems." I also found this link that noted "chlorine dioxide disinfection appears to be more applicative to maintain a biological stable drinking water."

CLR is made of Lactic Acid and Lauramine Oxide. So that also doesn't fit with the Chlorine Dioxide requirement. So now I'm on the hunt for some chlorine dioxide to try as a last attempt to really get this puppy clean.