The real reason you are not supposed to use tap water is that fresh tapwater has chlorine in it and if, like me, you fill your machine just before retiring for the evening the first thing to evaporate out of the water is the chlorine. Some people have had nasty turns from chlorine actually poisoning them, best bet is to fill in the AM and allow to stand till bed time or use cooled boiled water, Distilled or deionised water is really expensive if you use a litre every 2 or 3 days....
Vinegar will remove any "limey" deposits in the water tank, but rinse throughly before use.

what about rainwater Basil?????

Another reason for using a silver/activated charcoal filter. The tea and coffee taste so much better too.

Rolly wrote:

---

Another reason for using a silver/activated charcoal filter.

The tea and coffee taste so much better too.

---

Do they remove the chlorine? I have a HUMUNGOUS filter on the outside wall of this new house and it's plumbed through to the kitchen yes tea & coffee does taste better.

 

Perth water is often more loaded with chlorine than your average public swimming pool.

That's where the filter really earns it's price.

I often fill a bucket with filtered water as a final rinse-off in the shower as my skin gets all flaky with exposure to chlorine.

Fortunately, the heavy chlorination usually only happens in high Summer and the mains water comes out tepid anyway. 

OK Basil I give up - whats a CPAP machine - (I originally misread it to "CRAP" machine)

Continuus Postive Airways Pressure (CPAP) machine for sufferers of sleep apnoea.

Its an aircompressor for humans......... LOL LOL

My husband uses a CPAP machine too, but his doesn't have a humidifier. If it did, we would only use filtered water in it. We have one of those bench top water coolers in the kitchen, and originally bought it when wayward leaves in the strainer over the rain water tank released tannins into the water. Rather than lose a whole tank of rainwater, we invested in a cooler with a ceramic filter. You can get the coolers in all different sizes and the ceramic filters do a top job. When caravanning, we have a filter attached to our water supply in the van.