the guy was exaggerating. You can wash your car at home reasonably. You'll be fined only if the water was overflowing to the street ( someone might report you in that).
Checkout more water tips at Kahramaa web site
http://www.kahramaa.com.qa/NR/exeres/0FDC64A0-27DD-4B7F-8169-B3D5322078C...