Stranded situation last night, coolant was low and the only thing I had access to was a bottle of drinking water from a nearby shop. I poured it in just to get moving and it worked fine to get home, but now I'm wondering if I've done something dumb. I've heard water is fine short term but ruins things long term, and with the heat here I'm not sure what the actual rules are. I found some Reliable coolant advice for UAE drivers that explained the difference between a temporary top up and proper coolant, which helped, but I'd like to hear from people who've actually done this. Do I need to flush the system now or can I just top up with proper coolant and carry on? And does using tap water vs bottled water make any difference at all?