Why every drop of water is important

By MUNGAI KIHANYA

The Sunday Nation

Nairobi,

22 May 2016

One of the taps in my house doesn’t close tightly enough and it so has a very slow leak. I have ignored it for several months now but, recent one evening, an empty bowl was left in the sink directly below the tap and, in the quietness of the night, I heard the rhythmic sound of the drops landing: drip…drip…drip…

Now, after many years of hearing the regular one-second tick-tock of clock, our auditory system gets used to this rhythm. So, when something pulsates at a different rate, our ears tend to exaggerate the sound and it can make you lose you sleep. There are rumours that leaking taps are used as torture implements: the sound can drive you mad!

Going back to the tap in my house; I decided to estimate the dripping rate. The correct scientific way to do that involves timing how long it takes for a large number of drops – say 20 – then dividing the recorded time by that number minus one. The one is subtracted because we are interested in the time interval between two drops. There are 19 intervals in 20 drops.

But it was the middle of the night and I was not about to get out of bed to count water drops: I’m not that mad! So I used an age-old method to estimate the time. The duration of one second is approximately the time it takes to say the phrase “one hundred and one”.

Saying “one hundred and one – one hundred and two – one hundred and three” will take you about three seconds. Try it out and see. You can now appreciate why it is impossible to say all the numbers from one to one billion within a lifetime…but I digress.

I discovered that it is difficult to count by heart and listen at the same time, but it is not impossible. After several trials, I reckoned that I could only say “one hundred and one, one hundred and two, one hund-” before the next drop landed.

Thus the interval between the drops was about two and a half seconds. There are 60s in one minute so, at 2.5s intervals, we get 24 drops per minute. But we must add the las one, so we have 25 – a “nice” number to work with. Thus in one hour there were 1,500 drops and in one day 36,000.

The obvious question then is: how much water was I losing through the leakage? To answer it we need to know the volume of one drop. Believe it or not, there is a scientific standard: one drop is 0.05ml. That is 20 drops make one millilitre.

If we divide 36,000 by 20 we find that the daily loss is 1,800ml. That is, 1.8 litres. In one month, I’m losing 54L. That’s almost three, 20L jerry-cans lost through and annoying dripping tap. Upon this realisation, I booked a plumber to come and fix it.