If you want to analyze the heavy metals by AAS or ICP, then acid digestion of samples will be very efficient. To determine nitrate UV-Visible spectrometer is widely used. TDS can be measured by Conductivity meter or by simple conventional method of boiling of water. Also there is some mathematical correlation of TDS with electrical conductivity.
You can follow the "Standard Methods for the Examination of Water and Wastewater" of "American Public Health Association (APHA)"
If you want to analyze the heavy metals by AAS or ICP, then acid digestion of samples will be very efficient. To determine nitrate UV-Visible spectrometer is widely used. TDS can be measured by Conductivity meter or by simple conventional method of boiling of water. Also there is some mathematical correlation of TDS with electrical conductivity.
You can follow the "Standard Methods for the Examination of Water and Wastewater" of "American Public Health Association (APHA)"
Nitrates in the water samples you can determine by UV-Visible spectrophotometer. For determination the thermotolerant coliforms I think that Method 1604 by EPA: Total Coliforms and Escherichia coli in Water by Membrane Filtration Using a Simultaneous Detection Technique (MI Medium) should be a good option. For TDS there is a standard method (Standard Methods for the Examination of Water and Wastewater).
This is the website of EPA National Service Center for Environmental Publications: nepis.epa.gov. There you can find all the procedures by the number. The following references (websites) can help you: https://www.standardmethods.org/
Normal tests for lower atomic number contaminat elements can be conducted in enviornmental laboratory and for coliform bacterial in the microbiology lab and for heavy metals and rare earth metals,XRF spetrometer results can be analysed. The permissible limits can be compared with WHO norms. 2018
I wanted to neglect the fact you mentioned economical. But then I knew that standard methods exist for water quality studies , check Standard Methods for the Examination of Water and Wastewater. The stress is on standard methods. Therefore use AAS for the required parameters, get your water quality test kits and do the needful. Check out a publication on my profile on the impacts of urbanization on groundwater. I analysed for nitrates, TDS and conductivity too. TDS can be resolved with TSS/ TS
Leônidas Luiz Volcato Descovi Filho, TDS can be calculated by multiplying the EC value with factor from 0.5 to 0.70 in respect to the quality of the water sample used. If the water is clean and fresh then 0.5 factor can be used. If it is saline water then the factor could be 0.70.
In order to determine the water quality, the efficient methods of analysis are well described in "Standard Methods for Examination of Water and Wastewater", published by APHA. Here both economic as well as costly methods are there. In cases of analysis of micro amount, generally, costly and sophisticated methods are applied. Toxic substances are present in micro level and determination are costly.
Before discussing on the most economical and efficient way of analysing surface and Groundwater samples, it is important to talk about the sampling methods. They way and manner water samples are collected greatly affect the outcome of the analysis irrespective the instrumentation. The ICP-MC and GC are very effective, efficient and economical on the long run as a result of their high precision.
Yes I know that ICP-MC and GC Method is quite effective, efficient and economical but is there any place in Nigeria that have this type of high precision equipment. I am very interested in using it for my future research in water quality assessment. Thank you and Kind Regards