First Out of Warranty Maintenance -Advice?

[rufusdedog]

My warranty expired this month so I thought I would take care of maintenance things that aren't covered by BMW (or not very effectively). I have 35 K on the X5. I changed the air filter and spark plugs myself, and had the dealer change the coolant. It was a busy day at the dealer (Saturday appt) and I asked the SA if they used deionized or distilled water to mix with the coolant. He said he would check. Well, about 2 hours later, he told me the flush was complete and they use tap water to mix with the coolant. A conversation with the tech confirmed this. My question is- is this standard practice at the dealer? Will this cause any problems down the road?