A few days back, the managing committee of our society implemented restrictions on the usage of water. Which got me to do an experiment I was meaning to do since a very long time. The aim of the experiment was to understand how much water does an average household consume.

This experiment is not scientifically correct, but can give us a general idea of the usage pattern.

Methodology

  1. I used a regular plastic mug to measure water
  2. To mark the mug at the 500ml and 1L levels, I filled & emptied a 500ml cold drink bottle.
  3. I calculated the time it takes to fill the mug upto the 1L mark by fully opening the tap.

Water flow rates

  1. Wash basin taps: 17 sec/L (average of 9 readings taken across 3 wash basins)
  2. Kitchen tap: 15 sec/L (average of 3 readings)
  3. Shower: 5 sec/L (average of 3 readings)
  4. Flush: 4L / flushing (taken from jaguar website)

Implications

  1. Washing hands ~ 1 min = 3.5L
  2. Shower ~ 1 min = 12L
  3. Washing vessels ~ 1 min = 4L

For a family of four

  1. Hand washing : min. 4 times for ~ 1 min / day : 4 * 4 * 3.5 = 56L
  2. Toilet flush : min. 3 times / head : 4 * 3 * 4 = 48L
  3. Bathing:

    a. shower : min. 15 min / head : 4 * 15 * 12 = 720L

    b. Bucket bath : min. 2 buckets of 15 L = 4 * 2 * 15 = 120L

    c. Bath tub : Data Not Available with me

  4. Washing machine : 55 ~ 70 L / load ~ avg. 60L / load

  5. Dish washing :

    a. Machine : 10 ~ 20 L / load ~ avg. 15L / load

    b. House help : 25 min ~ 100L

  6. Wet mopping of house (including terraces) : ~ 4 buckets of water ~ 4 * 15L = 60 L

  7. Watering of plants : 2 buckets * 15 L = 30 L

Total consumption

  1. Excluding 3a, 3b, 3c, 5a & 5b = 254 L / household
  2. Depending on usage, addition of 3a, 3b, 3c, 5a or 5b can be done.

Remarks

  1. As per BIS 1172:1993, for a community population of more than 1 Lakh with a full flushing system is 150 - 200 lphd (Liters per head per day). From this 45L is assumed for flushing.
  2. if we assume that out of the 4 members, 2 members use a bucket and 2 use a shower for bath, ~ 420L is used for bath.
  3. Based on general perception, very few dish washers used, hence we add ~ 100L of water for dish washing.
  4. Total water consumption for a 4 member house goes to ~ 774 L
  5. We are hitting the upper level of BIS standards for water consumption.

References

  1. https://law.resource.org/pub/in/bis/S03/is.1172.1993.pdf
  2. http://jaquar.com/main/cat-no-flv-1015-flush-valve-complete-1
  3. Internet search for water consumptions by washing machine & dish washing machine.

Note

The real reasons for publishing the results of this experiment are aptly captured in this XKCD cartoon

Duty Calls