It is
difficult to establish the exact degree of the importance of water to man. It
is certain, however, that without water there would be no life of any kind on
the earth and that, without water readily available in adequate quantity and
free of pathogenic organisms, man’s progress is tremendously hindered. From a
public health point of view, there is no question that the aim should be to
supply quality drinking water to every family in the barangay. Access to safe
water can be achieved by protecting the main water sources, cleaning the water
reservoirs and by teaching water disinfection methods in the household levels. The
barangay is supplied by two protected and developed spring. Water from these
two spring lines is supplying the three main water tanks which then supply all
the households in the barangay. At this time, it was
noted that there were two points of weakness in the supply of drinking water.
First, is the contaminated water from the tanks and second, is the possible
contamination of the pipes that deliver the water from the tanks and tubod. This
is supported by water bacteriological analysis done from the main water
sources, water tanks and household samples. The problem in the quality of
drinking water in the barangay cannot be addressed by single intervention
hence, the team used a variety of approaches which includes water disinfection
promotion and water tank cleaning.
Prior to cleaning and disinfecting of the water tank, the
residents were informed that there will be no water supply for approximately 36
hours. With the help of the barangay’s water monitoring team, the announcement
was made two days before the actual tank cleaning and another reminder one day
before the actual tank cleaning. The tanks were cleaned and disinfected
following the WHO guidelines and standards.
Step 1- Cleaning the tank
a)
Draining/emptying the tank: The remaining
water in the tank was drained out by opening the outlet valve.
b)
Cleaning/scrubbing all internal surfaces:
An odorless antibacterial liquid detergent provided by the Department of
Science and Technology (DOST) and stiff brush were used to clean all internal
surfaces of the tank. The outlet valve was left open whilst cleaning.
c)
Washing all internal surfaces to remove
all traces of detergent: The tank was continuously flushed until there are no
longer traces of detergent that can be seen in the tank.
Step 2- Disinfecting the
tank
The total volume of the tank was computed to know how much
chlorine is needed in disinfecting the tank. The following formula was used:
Length x width x depth of
water x 1000 = number of liters
Tank 1
|
1.5 m x 1.5 m x 1.5 m x 1000
|
3375 L
|
Tank 2
|
2 m x 2 m x 2.5 m x 1000
|
10,000 L
|
Tank 3
|
2 m x 2 m x 2 m x 1000
|
8,000 L
|
Table 1. Tank measurement
and its volume capacity
a)
The tank was filled with clean water up to
¼ level only. In estimating the ¼ level of the tank, a stick with graded
markers was used to indicate the water level. The clean water was from the Tank
III since it is the only tank that passed the microbiological examination for
water. In cleaning the Tank III, water was drained out and retained up to ¼
level only.
b)
A concentrated chlorine solution was then
prepared to disinfect the tank. High test hypochlorite (HTH) granules or powder
was used as this normally contains 50-70% chlorine. A bucket was filled with 20
liters of clean water and a 50g of HTH was added to the water and stirred until
dissolved.
c)
The solution was poured slowly into the
tank, mixing it while pouring using the same stick with graded markers. 10
liters of the chlorine solution was added to the water in the tank for every
cubic meter of tank volume (1 cubic meter=1000 liters) and then the tank was
filled up to a full capacity of water.
TANK
|
AMOUNT
OF WATER
|
AMOUNT
OF HTH GRANULES
|
TANK 1
|
33.7 L
|
84.6 g
|
TANK 2
|
100 L
|
250 g
|
TANK 3
|
80 L
|
200 g
|
Table
2. Computed amount of water and chlorine granules needed for tank cleaning
d)
The tank was then closed and the chlorine
was left in the tank for 24 hours to ensure that the tank is fully disinfected.
e)
After 24 hours, the tank was emptied
completely and the disinfecting water was disposed properly. The waste liquid
was collected in a temporary pond and was mixed with sand. The mixed sand was
transported to a land fill area 1-2 kms away from the tanks and households for
disposal.
Step 3 – Chlorine testing
a)
The tank was refilled with clean water and
was allowed to stand for 30 minutes.
b)
The residual chlorine left in the tank was
tested by water analysis. A water sample from the disinfected tank was
collected and was sent to Zamboanga del Norte Medical Center for physico-chemical
and bacteriological testing.
Simple interventions were introduced to the residents
but these interventions made a huge impact to their lives helping them realize
the importance of having a safe drinking water.
