Design flaw.

[Spearmint]

You’ll have to rotate your screen, but really not happy that dirty rain water wells up under the back window.

[Jon_STLine]

Looks like I’m keeping a detailing brush in the mega box then

[gsd0475]

It also accumulates on the top of the rear diffuser.

[PaulD]

I haven,t seen it yet and we had a lot of rain lately

[Layters]

Hi Spearmint

I found this problem on the first clean, I used an old vac on blow to get the water out.
Used to have a similar problem on my Fiesta from both wing mirrors.
Come back an hour after cleaning to find water marks down the doors. I found rinsing the car with rain water helped,still dripped but left no dried on hard watermarks, as we live in a hard water area.

[Spearmint]

Yep, hard water too. Had the car spotless, then had rain and dust, everything on the car drifted back with the rain and landed on the lip, hence the build up