Assessing Water Quality and Its Relationship to Selected Disease Patterns in

: The research intended to establish the relationship between Zvishavane domestic water quality and selected disease patterns. Total levels of coliform, Escherichia Coli, chemical and other physical parameter levels in samples from selected water sources during the period March 2018 to January 2019 were evaluated. Zimbabwe National Water Authority (ZINWA) commercial laboratory methods were used to analyze thirty one randomly selected sources. This quantitative research results were compared with recommended limits from Standard Association of Zimbabwe (SAZS 560:1997) and World Health Organization (WHO).Five water sources had coliform counts ranging from < 1 to 55 cfu per 100 ml and Escherichia Coli from < 1 to 28 cfu per 100 ml. Chloride levels of above 200 mg/L were obtained from eight borehole water sources. Levels of selected heavy metal ions were within the SAZS 560:1997 maximum allowable limits in all water samples. Sample levels for Mg 2+ (29 %) and total hardness (32%) were above the maximum allowable levels. Tap water samples were within recommended limits for all measured parameters. Hypertension was first among the chronic disease conditions while diarrhoea and dysentery ranked second of the outpatient general diseases attended to at the Zvishavane District Hospital during 2018. 66 neonatal death were reported during the same time period. Zvishavane domestic water require research based pre-treatment methods before drinking. There is a possible link between the quality of water and the disease patterns. However these observations require further epidemiological studies to confirm the link.

Zvishavane is a small town situated in the central part of the Midlands region of Zimbabwe. The mining town which is surrounded by largely small scale to medium gold miners is also situated in what was a very active Shabani Asbestos Mine. An estimated population of 45 230 and a total of 12 370 households are found in the small town according to the 2012 national census (Compendium of statistics 2014). There was no other census that was carried out in Zimbabwe since that time till the present time (2019). Situated in the agricultural natural region three Zvishavane is associated with warm to hot temperatures (average 27 0 C) and infrequent rainfall patterns Chikodzi et al., (2013). The mean seasonal total infrequent rainfall for Zvishavane area is about 547 mm with a possible 745 mm and a minimum of 349 mm (Simba and Chayangira 2017). In Zimbabwe, urban councils and the Zimbabwe National Water Authority (ZINWA) are the major institutions responsible for service provision in urban areas (Zimbabwe report). Urban councils are responsible for the treatment and management of services from municipal water, sewerage and refuse removal departments while ZINWA is responsible for provision of raw water to the urban councils. The prevailing poor state of the Zimbabwe economy has made provision of general services to the population by local authorities in particular safe drinking water difficult (World Bank, 2017).
The Zimbabwe electricity supply is currently erratic affecting the drinking water pumping capacity at the water treatment and distribution stage thereby reducing normal pump flow at household level. The Zimbabwe government has stated that it is committed to the Sustainable Development Goal (SDG) number six on clean water and sanitation where it is expected that by 2030, safe affordable drinking water should be accessible to all (VNR, 2017). A base line study to assess the water quality from March 2018 to January 2019 for Zvishavane was carried out in this study.

MATERIALS AND METHODS
Two liter volume samples were collected from 30 different sampling areas (Figure 1) that were randomly selected from tap, surface and underground, around Zvishavane town as per ZINWA sampling protocol The analysis was carried out using ZINWA Assessing Water Quality and Its Relationship…..

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MULEYA, E; NYOMOMBE, T; MAPHOSA, NS; MATUNHU, V commercial laboratory standard methods of quantification (Table1). Samples were collected in March, May, July, September, November in 2018 and January 2019. We collected data of prevalent disease from Zvishavane District Health Information office.

RESULTS AND DISCUSSION
Escherichia coli and Total Coliform: Figure 2 shows that five sampling points during the period of study which reported high E. coli levels ranging between 4-23 cfu per 100ml. However all sampling points (tap water or bore hole) reported E. coli counts of between <1 to 29 cfu from the most contaminated sources during the period of sampling. The high levels of drinking water E. coli and total coliform count could explain why diarrhoea and dysentery are reported (Table 2) to be second on the top ten disease attended to during 2018 at Zvishavane district hospital with acute respiratory infections coming first of the reported cases.
.   Table 2 were obtained from the Zvishavane District hospital health information office indicating that diarrhoea and dysentery were second on a list of top ten conditions attended to in their outpatient department during 2018. Water with less than 1 cfu E.coli count is considered to be low risk for drinking (WHO, 2017) and SAZS 560:1997 guidelines state that its equivalent to zero count.
However when considering that in many cases consumers harvest tap water when available in containers at home for use when the municipal water is not available, the level of risk increases. Zvishavane being situated in a very warm region of average temperatures above 27 0 C, storage conditions could encourage the less than one colony to grow may be one of the causes of high incidence of diarrhoea shown by the hospital statistics in Table 2.

Turbidity, Total Dissolved Solids and Conductivity:
During the period of study only three samples reported very high turbidity, 13.9 NTU from the Clinic well source at 6.9 NTU, Masvingo road borehole and 12.94 NTU from Ngomeyebani borehole. The rest of all samples were below 5 NTU (SAZS 560:1997). However, for total dissolved solids, SAZS 560:1997 has no specified a limit but WHO recommended 1000 mg/L and 26% of the water samples readings were above that limit. All tap water sources were below the 1000 mg/L indicating that most of the possible contaminants were left at the water treatment stage. Water containing TDS level below 1000 mg/litre is usually acceptable to consumers (WHO, 2017). The palatability of drinking water has been rated by panels of tasters in previous studies in relation to its TDS level as follows: excellent, less than 300 mg/litre; good, between 300 and 600 mg/litre; fair, between 600 and 900 mg/litre; poor, between 900 and 1200 mg/litre; and unacceptable, greater than 1200 mg/litre (WHO, 2017). Water with extremely low concentrations of TDS may lack flavour and usually corrosive to plumbing systems (WHO, 2017). Conductivity is a measure of water's capability to pass electrical flow which is directly related to the concentration of ions in the water. About 82% of all conductivity readings during the study were above the stipulated recommended limit of 700 µS/cm but below the maximum allowable limit of 3000 µS/cm by SAZS 560:1997. This can be expected because of the high magnesium, calcium sodium and anion levels that were recorded.   Table 3. There is evidence from epidemiological studies for a protective effect of magnesium or hardness on cardiovascular mortality Stevanovic et al., {2017). Therefore despite the other risks such as E. coli contamination and elevated sodium levels in borehole water, the water may be of benefit as source of magnesium and calcium which can protect from cardio vascular disease and are also necessary in bone and teeth development in humans. Calcium levels vary from 227 mg/L (Manjere MSU borehole) to 7 mg/L Council Park tap water. There no limit for calcium in drinking water from SAZS 560:1997. Previous research has indicated that analysis concluded that hard water could be used to prevent ischemic heart disease (IHD) or coronary heart disease, through drinking Stevanovic S., et al., (2017) although high levels of magnesium could affect the water taste particularly in the presence of sulphate and chloride which is the case for Nil, Swift, Manjere MSU residence and East Vaal shops boreholes (Table 2).
In general, Zvishavane tap water sampled sources reported low sodium ion levels and are within recommended limits by SAZS: 560:1997 but the situation was different for boreholes because 52.38% of them reported sodium ion concentration of above 120 mg/L in sampled water. High sodium levels of 258.80 mg/L from Manjere Midlands State University (MSU) borehole in July 2018; 287.70 mg/L from open well source situated a private clinic and 995.00 mg/L from East Vaal borehole situated at a popular eatery. Zvishavane district hospital statics for chronic diseases (Table 3) indicate there is a link between the quality of water and reported disease conditions  Supply of safer tap water by Zvishavane town council municipality is erratic forcing consumers to rely on borehole water sources. If the Zimbabwe National Census Statistics of 2012 (much higher now, population growth rate was estimated to be 1%) of 45 230 people in Zvishavane town are considered, then the condition of hypertension is claiming 23.3% of the population.
Although there was a huge variation in nitrate concentration from one sampling episode to another, the averages indicated in Table 4 (Zimbabwe Health Information System, 2018), there is need for an epidemiological study to establish if there is a link between any deaths that the hospital experienced and water quality that was used for drinking by the pregnant mothers. Reports from previous research indicated that maternal drinking water nitrate intake during pregnancy could cause a range of pregnancy outcomes, including spontaneous abortion, foetal deaths, prematurity, intrauterine growth retardation, low birth weight, congenital malformations, and neonatal deaths Ward et al., (2018). Levels above 50 mg/L of NO -3 in water exposed infants to have been reported before to cause methaemoglobinaemia (leading to blue baby syndrome), thyroid effects and gastric cancer in adults Ward et al., (2018). Only one borehole reported above the recommended limit 258.8 mg/L during the month of July at Manjere MSU borehole (Table 4). Most water sources had chloride levels were within the SAZS 560:1997 recommended limits of 200 mg/L with 24.6% of samples above this limit and 0.04% reporting above the maximum allowable limits of 500 mg/L.

Conclusion:
There is a possible link between the quality of water and the reported disease patterns. The findings of the study recommend that due to the high incidence of hypertension reported by the district hospital, observations require epidemiological studies to investigate if high sodium ion levels in some borehole water samples are linked to any hypertension cases. Zvishavane drinking water needs further treatment before drinking especially the open well source.