The water project funded by the Fijian Government should
start next week. I wasn’t expecting it
to come through but it did, and everyone is very thankful. In order to see the impact I’ve been
analyzing the water usage prior to the improvements to evaluate the impact it
has on the community. Since there are no
meters, measuring the water use is somewhat a fuzzy science.
The main tank serving about 600 people was built in 1992 and
has a capacity of about 62,000 litres.
It is fed from two sources, both of which are artesian spring fed
streams. We’ve been told that when the
water source is blocked the tank it empties in 2 days. This put water use at 31,000 litres per day,
or 52 litres per person. This seems like
a lot until considering leaky taps, leaky pipes, or kids leaving taps on for
fun. There is also a lot of water used
in washing clothes as most have washing machines that do everything but spin
dry. These consume a lot of water.
My main reason I’m worried is the flush toilet roll out is
going strong. They have applied for a
grant for 80 flush toilets and if everything goes right they’ll start to be
installed next June/July. This will
increase the water use per person by 28 litres considering each flush uses 7
litres and a person goes to the bathroom 4 times per day.
The only way I could measure the water inflow to see what
the new demand would be was the bucket and stop watch method. I think this will work o.k. after the first
trial test. It is pretty simple. Just take a breakfast cracker bucket and fill
it in two litre increments marking the level as it is filled. Then take a stop watch and time how long it
takes to fill. Divide the litres by the
hour and you have the flow. Of course
this doesn’t take into account variations in flow from the source and assumes
it is constant. Hopefully after several
readings it will average out to be close to the same.
The first test showed 1,475 ltr/hr flowing into the tank
from the two sources.
To support their current and future use the community will
need about 3,500 ltr/hr which gives them a delta of almost 2,000 ltrs/hr.
The next step is measuring outflow which involved using the
cane knife. Any work involving the cane
knife is fun, except weeding my bele patch.
That isn’t fun. I wacked down a
bamboo trunk near the tank and marked off one foot increments, my tape measure
does not have meters. I then stuck the
bamboo into the tank and noted the depth and time. I plan on going back before peak usage starts
at 4pm and noting the depth. If I’m
feeling really motivated I will go back at 6pm after the evening peak usage is
over. The peak morning hours are 6 am –
10 am.
A book I found really helpful in measuring water flow was Engineering
in Emergencies, 2nd Edition, by Jan Davis and Robert Lambert. It has a lot of useful information about
basic, and some complex, engineering systems.
I’d recommend it for any volunteer.
A major battle is the quality of the infrastructure. A lot of the pipes are exposed leaving them
victims to solar and human deterioration.
Here are the two sources currently feeding the tank.
Vapor Trail 
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