1 WATER QUALITY Thursday 7 July: Session 1 Water quality issues for groundwater and their relationship to sanitation and health.Dr. L Katiyo (IWSD)
2 3/31/2017WHO DefinitionDefines safe drinking water as water that “does not represent any significant risk to health over the lifetime of consumption, including different sensitivities that may occur between life stages.”
3 Guidelines vs. Standards 3/31/2017Guidelines vs. StandardsGuideline: a recommended limit that should not be exceededStandard: a mandatory limit that must not be exceeded (often reflects legal duty or obligation)WHO Guidelines for Drinking Water Quality (2006)Guideline values to ensure safety of drinking waterStandards vary among countries and regions
4 Why Do We Do Water Quality Testing? 3/31/2017Why Do We Do Water Quality Testing?Ensure safe drinking waterIdentify problemsAdopt precautionary measuresRaise awarenessDetermine the effectiveness of water treatment technologiesSelect an appropriate water sourceInfluence policies to supply safe water
5 Categories of Contaminants 3/31/2017Categories of ContaminantsChemicalsMicrobiologicalPhysical
6 Categories of Contaminants 3/31/2017Categories of ContaminantsChemicalsOrganicInorganicpHMicrobiologicalBacteriaVirusProtozoaHelminthsPhysicalTurbidityColourOdorTaste
7 Water Sampling Microbiological sampling Indicator organisms for pathogen presencePhysical samplingturbidity, conductivity, total dissolved solids etcChemical sampling- pH, dissolved oxygen, phosphates, chemical oxygen demand, biological oxygen demand, mineral impurities (iron, manganese, chloride, lead, sodium etc)
8 Types of Testing Observation Field testing Advantages: Limitations: 3/31/2017Types of TestingObservationAdvantages:Quick and easyInexpensiveLimitations:Qualitative – low precision and accuracyField testingEasy to use and portableRapid resultsLess expensiveLess precision and accuracyLess quality assurance
9 Types of Testing Mobile laboratories Laboratory testing Advantages: 3/31/2017Types of TestingMobile laboratoriesAdvantages:Controlled environment,High level of precision and accuracyLimitations:Relatively expensiveRequires skilled laboratory techniciansLaboratory testingExpensiveLack of flexibility to conduct own testing
10 Selecting Test Methods 3/31/2017Selecting Test MethodsDepends on:ObjectivesRange of concentrationRequired accuracy and precisionTime period between sampling and analysisTechnical skills and equipment requiredFamiliarity with the methodAvailability of resources
11 Where Do We Sample? Source water 3/31/2017Where Do We Sample?Source waterTransport container (before treatment)Treated waterStored water (after treatment)Point of useSee Manual Section 3 on how to sample different sources.
13 micro-organism that cause disease Pathogensmicro-organism that cause disease4 types of pathogensBacteriaVirusProtozoaHelminthsZoom: Bacteria on the tip of a pin
14 Size Comparison Smallest Largest Virus (0.02 to 0.2 micron) Virus BacteriaBacteria (0.2 to 5 microns)ProtozoaHelminthProtozoa4 to 20 micronsLargestHelminth40 to 100 micronsRepresentation of the relative sizes of different pathogens, and the pore size in a sand filter.Pathogen size is very relevant to understanding filter technology.Pore size in a sand filter (1 micron)
15 Viruses Hepatitis (A and E are faecal-oral) Dengue Fever Polio Viruses depend on the host cells that they infect to replicateWhen stimulated, new viruses are formed, and burst out of the host cell, killing it and going on to infect other cellsSome viruses can remain viable outside of a host for long periods, also in dry conditionsViruses can survive but will not grow in foodThere is a dispute over whether viruses are living or not. Generally accepted that viruses are not living but contain a “recipe” for a form of life; require a host cell, contain genes, self assemble rather than reproduce, evolve and adapt through a process of natural selection.
16 Bacteria Cholera E-Coli Salmonella Shigella Typhoid Trachoma Most of the organisms found in feces are bacteria. There are several billion bacteria in every gram of feces.The diseases they cause generally spread rapidly, and consequently bacteria have been responsible for most of the world’s major epidemics derived from water.Two of the most well known diseases caused by bacteria are typhoid fever and cholera. Can you think of any more?They are the simplest, wholly contained life systems.There are many different types of bacteria.They have different sizes and shapes, but are generally between 0.3 and 100 microns in size.There are many more bacteria that do not normally cause disease – e.g. yeasts, cheese, beer. Food safety standards for cold sliced meats – <10,000,000 heterotrophic bacteria per gram.Most dominant organism found in faecesMost diverse group of micro-organismsSimplest, wholly contained life systemAbundant in faeces (1g = billions of bacteria)
17 FACTORS AFFECTING NUMBER AND TYPE OF BACTERIA IN WATER Type of water:Surface or deepMineral springsPresence of organic matterTemperatureLightpHDissolved oxygenRainfallSeasonStorageFiltration
18 Protozoa Single celled organisms Able to form cysts which are resistant to chlorineSome can stay alive outside of a hostProtozoa are larger than bacteria or viruses.They are single celled organisms which can form cysts or vegetative states that can survive in inhospitable environments.Because of this, they are difficult to kill with chlorine.Most of the major waterborne disease epidemics in the North America over the last ten years are due to protozoa. This is because they can survive the chlorination process used in municipal water treatment plants.Two of the more well known protozoa are giardia and cryptosporidia.GiardiaCryptosporidiumMalaria
19 Helminths Roundworm Hookworm Guinea Worm Schistosomiasis (Bilharzia) Worm from a human intestine (20 feet in length)Can live for many years in the bodyMost do not multiply within the human hostDerives sustenance at hosts expenseMost helminths are passed in faecesHelminths are parasitic worms.One of the most well known diseases caused by helminths is schistosomiasis which is prevalent in most parts of Africa.Many worms can survive in the body for several years. They make their host weaker by using his food supply to grow.They generally do not multiply within the human host.Most helminths are passed in faeces.Protozoa and helminths are known as parasites.
21 Microbiological Testing Testing for every pathogen is time consuming and expensive
22 Bacterial Indicator Organisms Test for bacterial indicator organisms instead:CheaperEasier to performFaster resultsDoes not require highly trained personnel
23 Bacterial Indicator Organisms Good indicators should:Be present whenever pathogens are presentPresent in the same or higher numbers than pathogensSpecific for faecal contaminationNon-pathogenic (harmless)Have a survival time equal to pathogensNot reproduce in water
24 BacteriaHeterotrophic Bacteria: Most bacteria in nature, includes all pathogensTotal Coliforms:Presence in water may indicate contaminationThermotolerant Coliforms: Found in intestines of warm-blooded animalsE. coli: Indicator of fecal contamination
25 Indicator organisms: Esch.coli. Faecal coliforms Faecal streptococci. Clostridium perfringens. Presence of fecal streptococci along with coliforms in the absence of E.coli is also confirmatory of fecal pollution.
26 Escherichia coli (E. coli) Found mainly in faeces of warm-blooded animalsMajority of E. coli is harmless (non-pathogenic)Meets criteria for a good indicator and is the most importantMost specific for faecal contaminationLimited ability to survive and reproduce in waterNon-pathogenicE. coli O157:H7 is an exception – causes severe diarrhoeaE. coli O157:H7 does not produce this enzyme and cannot be detected by normal test methods
27 WHO Guidelines Number of E. coli Present (CFU/100 mL) Risk 0 - 10 Reasonable QualityPolluted,000Dangerous> 1,000Very DangerousSource: WHO, 1997; Harvey, 2007
28 Microbiological Testing Methods 3 methods to determine presence of bacteria in water:Presence-Absence (P-A)Most Probable Number (MPN)Membrane Filtration
29 Presence-Absence (P-A) Simplest methodAdd water sample to a bottle containing broth and let it sit for hoursColor will change if indicator organism is presentDoes not show numbers of bacteria!If the sample is positive, the water should be re-tested using membrane filtration to determine the number of bacteriaNot recommended by WHO for analysis of surface water and untreated community water suppliesNot recommended for testing the efficiency of household water treatment technologies (e.g. biosand filter)
30 Positive for Coliforms Presence-AbsencePositive for ColiformsPositive for E. coliNegative
31 Most Probable Number (MPN) Tells the number of bacteria that are most likely to be in the water sampleAdd water sample or diluted sample to 5 or 10 or test tubes (or larger tray 50 – 96 tubes)Incubate for hoursGas production and/or cloudiness will be visible if the indicator organism is presentUsing a table provided, report the number of positive tubes as number of colonies per 100 mL of sampleTypically used for wastewater or turbid samples
32 Most Probable Number (MPN) # PositiveTubesMPN Index(CFU/100mL)<22.214.171.124.645.156.969.2712.0816.1923.010>23.0Sample Table for 10 tube test
33 Most Probable Number (MPN) Characteristics:Quantitative resultsSimple to understand and useRelatively inexpensiveCan be used with turbid waterMore labor-intensive than P-ARequires some trainingRequires incubator & other equipment
34 Membrane Filtration Most accurate method to count bacteria Filter 100 mL of a water sampleAdd broth to a Petri dish which provides nutrients for the indicator organism to growFilter the water using the filtration equipmentTransfer the filter paper to the Petri dishIncubate for hours depending on the brothIf the indicator organism is present, colonies will appear on the filter paper and can be countedResults are reported as the number of colonies per 100 mL of water sample (CFU/100mL)CFU = colony forming units
35 Membrane Filter Technology 35Membrane Filter TechnologyA membrane is a thin material that has pores (holes) of a specific sizeMembranes trap larger particles that won’t fit through the pores of the membrane, letting water and other smaller substances through to the other side
38 Transporting Samples Bacteria do not survive well in water 3/31/2017Transporting SamplesBacteria do not survive well in waterTemperature can affect bacteria die offSamples should be placed on ice in an insulated container if they cannot be tested right awayIdeally – all samples should be tested within 6 hours of samplingIf the time exceeds 6 hours, note this in your reportSamples exceeding 30 hours (between collection and testing) should not be tested
42 Membrane Filtration Advantages: Able to count the number of bacteria Most accurate test methodAbility to test many samples at onceInternationally recognized methodRapidEasy & Economical.Gives direct result.Useful in rural areas.Samples can be tested in the field
43 Membrane Filtration Limitations: More labour intensive than MPN, P-A Requires more trainingRequires additional equipmentCost of consumables can be high in many countriesTurbid water interferes with bacterial growth.Noncoliforms interferes with counting of coliforms.Toxic substances in the water may be absorbed by filter and interferes with bacterial growth.
44 Sampling from a dugwell: Sampling from a dugwell: A suitable size stone has to be attached to the sampling bottle. A 20 meter length of clean string is tied on the bottle and a stick. Bottle is immersed completely in the water and lowered down to the bottom of the well. Once the bottle is filled ,it is pulled out. Little water is discarded to provide air space.
45 Sampling bottles and bags 3/31/2017Sampling bottles and bagsWhirl-pak® bag(from 120 to 720mL)Plastic Sample Bottles(from 200mL to 1500mL)ConvenientSingle UseMore robustRe-usable
46 Processing of the sample:. Should be processed within 6 hours Processing of the sample: Should be processed within 6 hours. In case of delay ,water can be filtered by using a membrane filter. Filter paper has to be transported on an absorbent pad saturated with transport medium.
49 What is Turbidity? A measure of water clarity The murkier the water, the higher the turbidity.Turbidity reduces the transmission of light into water.Turbidity increases as a result of suspended solids in the water.
52 How is Turbidity Measured? Secchi diskMeasures water transparencyMeasures depth at which disk is no longer visibleUseful for deep water
53 Turbidity in the lab and field Turbidimeteroptical device that measures scattering of light (most accurate)Measure in NTU (nephelometric turbidity units) or JTU (Jackson turbidity units)
54 Typical Turbidity Data Water SourceTurbidity LevelWater bodies with sparse plant and animal life0 NTUDrinking water<0.5 NTUTypical groundwater<1.0 NTUWater bodies with moderate plant and animal life1 - 8 NTUWater bodies with large plumes of planktonic life10 – 30 NTUMuddy water or winter storm flows in riversNTU
55 So what? Degrades drinking water quality. Water treatment costs increase.Decreases light penetration in water.
56 ConductivityConductivity is the measure of water’s ability to conduct an electric current.Estimates amount of total dissolved minerals (ions).
58 Conductivity in waterDissolved salts (ions) conduct electrical current in water.Absolutely pure water is a poor electrical conductor.
59 How do we measure Conductivity? Test with a Conductivity meterMeasured in Siemens or mhos/cm
60 Conductivity UnitsMhos is ohms backwards! (Mhos is the reciprocal of ohms –if you have to know)So….ohms is a measure of the resistance to a current.The less the resistance, the greater the conductivity.Conductivity in drinking water is low, so we use µmhos/cm or 1 x 10-6 mhos/cm!Units are sometimes expressed as microsiemens (µS).
61 So What? Increased concentration of salts increases the conductivity Salts cannot be filtered outHigher conductivity can.…Foul irrigation water (leads to high salinity soils)Kill wildlifeCreate water shortages
63 pH testing tap waterTap water is probably close to being neutral (pH 7), so we will use the two test papers that include pH 7 in their range. pH will be good if the water is somewhat acidic. pH will be good if the water is very slightly acidic to somewhat alkaline.
64 pH testing tap waterLet's say we start off with the pH paper. Dip the paper into the beaker with the tap water for just a couple of seconds. Then take it to the chart.
65 pH testing tap waterIt looks like the pH is between 6.8 and 7.1. So it's looks pretty much neutral. We can now try the other test paper (pH ) for confirmation.
66 pH testing tap waterThis is the pH paper for the range. Dip in the tap water for a couple of seconds and take it to the chart.
67 pH testing tap waterThe pH paper turns dark blue which indicates that it was close to the 7.0 pH reading. So it appears that the two different pH test papers both point to a pH close to the neutral pH of 7. This is usual for tap water unless there is something wrong with the water supply.
70 HardnessWhen hard water dries, you see a lot of these salts left behind. When it dries on a window, it's all spotted. The salts are mostly calcium carbonate (chalk), calcium chloride (deicing salt), and sodium chloride (french-fries salt).
71 Hardness and Alkalinity A hardness test is mostly measuring the amount of calcium in the water. An alkalinity test is measuring the amount of carbonate in the water. So both tests are targeting calcium carbonate; one measuring calcium and the other measuring the carbonate. So they both are very similar.
72 Hardness and alkalinity A hardness test is mostly measuring the amount of calcium in the water. An alkalinity test is measuring the amount of carbonate in the water. So both tests are targeting calcium carbonate; one measuring calcium and the other measuring the carbonate. So they both are very similar.
73 Odor and Taste? What are some common odors/tastes? How is it measured? Earthy, musty, moldyCan be produced by some types of bacteria (actinomycetes)May occur after adding chlorineGrass, hay, straw, woodAssociated with algal byproducts – decaying vegetationMarshy, swampy, septic, sewage, rotten eggSulphur – human or naturalChlorineResidual from water treatmentHow is it measured?Use your sensesDo not breathe in the smell directly, use your hand to waft vapors towards your nose
74 Colour? Reddish, brown, or yellow Black Dark brown or yellow Foam iron bacteria growthmanganeseDark brown or yellowIndustrial waste from tanning industry, pulp and paperDecaying vegetationsFoamdetergents
76 Chemical testing of water Chemical Testing MethodsTest stripsColour disc comparatorsColorimeters & photometersDigital metersArsenic specific kits
77 Chemical TestsThere are many different chemicals that can be found in our drinking waterDifficult and expensive to test for all chemicals so we need to select a few that are a priority in the local areaIron, ManganeseArsenic, FluorideChlorineTotal Dissolved Solids
78 Iron and Health Need small amounts of iron in food to be healthy No health impact, no WHO Guideline value> 0.3 mg/L of ironCauses a bad tasteStains water pipes and well apronsStains clothes during washing
79 Manganese Naturally found in groundwater Water has a black colour or black flakesCommon to find manganese and iron together in water
80 Manganese and Health Need some manganese in food to be healthy Too much or too little manganese can make people sickWHO Guideline value < 0.4 mg/L> 0.15 mg/L of manganeseCauses a bad tasteStains water pipes and creates a coating that comes off as small black flakesStains clothes during washingStains food during cooking
82 As: Where does it come from? Anthropogenic or Man-Made:Drilling WellsMineral ExtractionProcessing WastesPesticidesLevels of As in water depend on:Level of human activityDistance from pollution sources
83 Arsenic and Health Light or dark spots on skin Hardening skin on palms and feetCauses cancerBabies and young children are most vulnerableBiggest chemical issue in developing countries, high priority for WHOWHO Guideline < 0.01 mg/LStandards vary between countries
84 Non-Cancer Health Effects Long-term As exposure was found to be associated with cardiovascular effects (Utah and Taiwan)As exposure has also been reported to cause hypertension, anemia, liver disorders, kidney damage, headache, & confusion.Among children there have been reports of intellectual impairment when As in drinking water exceeded 50 µg/L (Bangladesh)
87 Fluoride and HealthHelps make teeth strong and prevents decay at low doses (0.5 – 1.0 mg/L)Higher doses are not good for teeth (1.5 – 4.0 mg/L)Very high doses harms the skeleton (> 10 mg/L)WHO Guideline < 1.5 mg/L
88 ChlorineCommonly use chlorine as a disinfectant to treat drinking waterNot usually found naturally in water in amounts that can cause harmWHO Guideline < 5.0 mg/LHigh amounts of chlorine can hurt skin, eyes, throat and lungs if we touch it or breathe it
89 Chlorine for Disinfection Two things happen when we add chlorine to water:Some chlorine reacts with organic matter to form new chemicals – Combined ChlorineSome chlorine is left over – Free ChlorineTotal Chlorine = Combined + Free
90 Chlorine for Disinfection Consumed chlorine is what kills pathogens in drinking water.Free chlorine is what protects drinking water from re-contamination.Ideal level of free chlorine in drinking water: 0.2 – 0.5 mg/LTypical levels of free chlorine in drinking water are mg/L
91 Chemical Test Methods Test (reagent) strips Colour disc comparators Colorimeter and photometerDigital meters
92 Test (Reagent) Strips Designed to react with specific chemicals pH, chlorine, hardness, etc.Compare colour on stick to colour chartAdvantages:InexpensiveEasy and simpleProvides rough estimateLimitations:Requires visual interpretation of colourLow accuracy +/- 10 %
93 Colour Disc Comparator Designed to react with specific chemicalsChlorine, fluoride, nitrates, etc.Interchangeable colour discsAdvantages:Can be done in moderate field conditionsBetter accuracyLimitations:Need reagentsMore expensiveRequires visual interpretation of colour
94 Colorimeters & Photometers Photometer (Wagtech)Uses light source to measure chemical concentrationTest a range of chemicalsAdvantages:More accurateLimitations:More expensivePower source necessaryProper training requiredColorimeter (HACH)
95 Arsenic Test Kits Designed specifically for arsenic Advantages: Fairly accurate – range 2 to 100 ug/LPortableRelatively easy to useLimitations:Requires visual interpretation of colourExpensive
96 Sampling frequency… Depends on… • The quality of the water source and the type of treatment• Size of the population served by the water source or distribution system• Outbreak of diseases in the community served. If outbreaks occur frequently then the sampling frequency should also be higher.• Resources available• Type of water source• Probability of contamination of water source• Use of water
97 What is Safe Water?3/31/2017Facilitator can ask the audience how they would describe good quality and poor quality water.