Everyone we know here in Malaysia has water filters installed in their houses - normally a big one outside and another one inside. In fact the water quality situation has given rise to a huge industry here in Malaysia with several companies offering a range of water purifiers and filters - I guess the most popular ones are the reverse osmosis machines costing thousands of dollars.
Soon after we got back from the UK and moved into our rented house, we too realised that we needed to install water filters. It was costly but it was absolutely necessary considering the terrible quality of water.
It was not this bad when we left the country nearly 9 years ago. Moreover, the water supply was privatised and theoretically the service and quality ought to be better. Unfortunately, this is not the case. The quality of water has literally gone down the drain. Not sure what the problem is due to - is it due to old rusted pipes?
Look at the backwash of our external filter just after one week. It looks like black coffee.
The authorities seriously need to do something about this.