Can I water my Mexican Pinguicula with tap-water?

[Wolfn]

Can I water my Mexican Pinguicula with tap-water? Mexican butterworts are known to grow in richer soils, so I'm wondering if watering them with tap water would harm them.

Should I try tap water or stick with rain water?

 

[jimscott]

Stick with rain water unless you know the chemical makeup of your tap water.