An excellent advice from you lawyer...????
Yes, buy a fair size water tank compared to how many people living in the house, a small 500 liter tank with a floating valve might be enough and that might cost in the area of 6,000 baht; a pressure pump for water-pressure in the house, which can be a fairly small pump for around 4,000-6,000 baht if you are only 2-3 people living in not more than 2 floors, have the pump installed so it can be easily exchanged as lifetime might be somewhere between 5 and 10 years; a small clear filter-house for a 5-10 micron filter to clean the water coming into the house, mounted after the pump, filters need to be changed weekly or fortnightly depending of the amount of dirt and alges, filters can be bought for less than 30 baht a piece from either DIY or Lazada; a pair of good quality plastic valves, so you can close water pressure when changing filter, they might cost about 400-500 baht each...????
The photo below shows the type of filter-house – the one shown is one I have on my water tank the attic with an UV-lamp, just shown for the type – it costs about 600-700 baht...