Physicochemical Analysis of Tap Water in Tepi town, Southwest Ethiopia

Abstract

Physicochemical analysis of tap water was carried out in Tepi town southwest Ethiopia. After
digestion with microwave acid digestion, some selected metals (Mg, Ca, Cu, Mn, Fe, Zn, Cd
&Pb) were determined using Flame Atomic Absorption Spectrophotometer and some selected
common anions were determined as follows, Ortho phosphorous (PO4
-3) by APHA4500-
PC.Vanadomolybdphosphoric method, Chloride (Cl-) by APHA4500-Cl-B. Argentometric
method, Carbonate (CO3
-2) by APHA 2330B. Titration, Nitrate (NO3
-) and ammonia (NH3) by
WTD photometer method (WAG PHOT-24). The mean temperature of all water samples were
ranged between 24.50 + 0.38 OC to 27.50 + 0.60 OC, which was found above the European
Commission (EC) standards (12- 25°C) set for waters used for drinking purpose. The pH of
water samples were lied from 6.62+0.06 to 7.89+0.10. This was within the prescribed
recommended limits of WHO guideline. The Conductivity (EC) values of all water samples
were ranged between 87.8+0.47- 313.5+0.6 μs/100ml. When compared to WHO standard,
the analyzed results were within the maximum admissible limit that allow to consume water
with EC up to 250 μS/cm. The total hardness value of all water samples were found above the
recommended value, which ranged from 685+1.76 mg/L to 792+1.84 mg/L. These selected
major, minor-essential metals were present in the water samples. From the toxic metals Pb
was not detected in all water samples but Cd was detected in distribution points (reservoirs)
but not on the distribution systems (households) of the study area. The concentration of Mg
(246.8 + 0.002 ppm) was higher followed by Ca (8.581+ 0.013ppm) in water samples. The
levels of minor – essential metals in this sample, Fe (6.521 + 0.001 ppm) was higher followed
by Mn (6.41 + 0.001 ppm), Zn (1.354 + 0.009 ppm) and Cu (0.162 + 10-5 ppm) respectively.
Cd was detected in water samples of reservoirs with a maximum concentration (0.045 +
0.005) and the concentration of Pb was below the method detection limit in all the water
samples. According to WHO guidelines the rages of these selected metal ions were on safe
side except Cd. Under this investigation, at p = 0.05, the physicochemical parameters of all
water samples which were taken from different sites were significantly different among the
distribution points distribution systems.