I've mistakenly put washer concentrate in my brake fluid reservoir?

You could use a turkey baster and suck fluid out of master cylinder and refill with new fluid
But it would be better to bleed sytem amd refill with fresh fluid
Some places recommend a fluid flush about every 30,000 miles which I agree with ......have done alot of brake work and after about 30,000 its gets pretty black in color showing its picking up trash ....will proably be saving money on replacing wheel cylinders and calipers in the future too

bg
February 2006