According to the bar chart in 2005, private houses in Singapore consumed 33 cubic meters of water per month. On the contrary, 1 to 3 rooms high density building (HBD) flats
consumed less than the half amount. What do you think what was the reason behind this?

Good city planning, money and population per capita.

Explanation:

I believe this has to do with better city planning and the other reasons above. This is because Singapore is one of many cities to implement a more greener approach to city building compared to other cities, especially when it comes to high density buildings. These buildings are better known for their efficient use of things like water and power, while most privately owned residences are not. Depending on who owns these homes, there are a few more reasons.

If you had the money, hiring maids is an option. It was found that house maids use up a lot of water for things like washing dishes and laundry. These use water and therefore increase the household use of it.

Another final reason is based on how many people live in these homes and flats. Depending on size, more or less persons could be living in these areas, decreasing the amount of water used.

Hope this helps.