It sounds very complicated.

Its a lot easier just putting a strong lime cordial in the tap water so you can't taste anything else....but filtered water for single malt is a must.

I thought what came out of the tap was for cleaning and what came out of a bottle was for drinking (provided it says "brewed in" somewhere on the bottle). Is that simple enough BB?

I'll stick with Tesco mineral water

Given that our shower head recently clogged up with some kind of jelly in the water supply I will be sticking to my policy of only drinking bottled water.

Tap water in Malaysia is officially safe to drink. I have been going in and out of Malaysia since 1971 and have always drunk tap water. Incidentally if it was not safe to drink it would not be safe to clean your teeth either.
Bottled water, which first appeared in Malaysia in the 80's I recall, is a clever marketing con based on scare mongering about tap water.
Those companies even manage to sell bottled water in the UK which has some of the safest tap water in the world.

The year 1971 is the year yours truly was born!

Wowsers! You have been here for > 40 years?

The tap water in Penang is clean. Not sure about other areas of MY.
But, the main concern is not the water, but the water tanks that the water is stored in.
In the condos I've stayed in HK they have regular maintenance of the water tanks and a notice to every units that they will be doing the cleaning on such a day and asked all residents to run the tap for a bit after that to clear out the pipes first.
Here, I've asked management about the water tanks maintenance and they looked at me with a very surprised "big eyes" ;0)

Well it certainly appears clean but it tastes just awful unless mixed with lots of toothpaste.

I remember using nylon stocking material tied over the spout of the tap, that is the lumps removed, then what water gets through is boiled. It seemed to work very well a few years back.

Those of a neurotic disposition may wish to buy bottled water or invest in equally dubious filtration systems. I would prefer to trust the old technology.

Yes same as bakedbean cleaning teeth using tap water is fine, as you do not swallow it, we also always use 1.5 litre bottle water for general drinking we buy a couple of boxes a time & its delivered for free. Tap water is boiled for tea coffee etc no problem.

Remember filtration you really need two units one to take out the rust & lumps this is normally fitted at the main inlet, then another to kill the bugs, this gets fitted at the taps, then of course you have to continually replace filters on a regular basis that's why we ended up not bothering.

I assure you that if there were nasties in it just putting it in your mouth and not swallowing would not be fine.

For our drinking water I have a ceramic/carbon filter connected at the tap and that is all.
Sometimes (each 3-4 months) I clean it. Especially after the tanks in the condo have been cleaned so there is a lot of brown goo on it).
So far no problems, but maybe it is not good for young people or pregnant ladies.

I don't think your water filter kills any bugs, it just removes some chemicals (and adds some back for good measure)!