Water Testing
For Domestic, Dairy Shed, Stock and Horticulture.
Includes:
· Acidity or Alkalinity,
· Faecal contamination,
· Soil bacteria contamination,
· Corrosiveness,
· Dissolved solids,
· Turbidity,
· Fertilisers N.P.K.S,
· Salt water or soda water effects,
· Hardness and scale forming probability,
· Giardia probability,
· Odour problems,
· Taste problems,
· Hardness,
· Dissolved metals.
Suitable for:
· bore, spring, stream, well, roof caught,
· dam or other supply used for domestic purposes.
Sampling.
· The laboratory has suitable containers for collection of samples available free to clients. If this is inconvenient then select a suitable container, 1 to 2 litres with a good sealing cap, Agee jar, milk or soft drink bottle, freshly empty. Rinse the residue from the container thoroughly, pour boiling water into the container to kill any background bacteria (as if preparing for preserves)
· Generally the sample should taken from the kitchen cold tap after running it for several minutes.
· Fill the container to the top and cap tightly. Refrigerate if the sample cannot be delivered to the lab immediately.
Note. . The quality of the result is effected by the cleanliness of the sample bottle and the age of the sample when received in the laboratory.
Background.
Nature provides the Earth with a fairly constant supply of minerally pure and sanitary water from rain. As the rain returns to the oceans it becomes contaminated, first by its coarse across the land into streams and dams , into underground aquifers and eventually back to the sea. A contaminated roof caught water may be as pure as a fast flowing stream, which when contaminated may increase in mineral content to a level expected of an average bore water, as the mineral contents of bore water increase they begin to take on the fingerprint characteristics of sea water. Any water regardless of its mineral purity can become contaminated with bacteria. Bacteria don't have much influence on the chemical nature of water but the chemical nature of a water can attract a particular type of bacteria and provide ideal conditions for that bacteria to flourish. (iron and sulphur bacteria are common examples.)
Results.
A bargraph is used in conjunction with the result to give a indication of the significance of the result. As the result increases becomes greater the bargraph indicates if this level is low, medium or high .
pH ................The acidity or alkalinity of a water is determined by the presence and concentration of minerals dissolved in that water. Generally hard waters tend to have higher pH’s than soft waters.
pH levels less than 6.0 are often associated with corrosion although corrosion can occur when the pH is greater than 7.0.
Turbidity is a measure of light which is defracted by suspended particles in a water. These particles can be dirt or high levels of bacteria. These suspended particles have the potential to block filters. Particle size has a greater effect on filter blocking than the number of particles.
Corrosiveness (corrosive index) The failure of a hot water cylinder due to pin hole’s is a sure sign of a corrosive situation. Blue or green staining of taps, basins and baths, or bitter tasting water first thing in the morning are all further signs that the household plumbing is in a state of decay. The cause can be related to the household electrical wiring. The incorrect use of different metals in the plumbing or the water is simply corrosive. A combination of the above is also possible. The corrosiveness index calculates how much copper will be corroded. Corrosion is caused by 3 separate situations or combinations of all three. Acidic pH or oxidising minerals, a mixture of non compatible metals (iron and copper) or the plumbing is poorly earthed and electrical current is passing through the water.
The results are capable of indicating the likely lifespan of the hot water cylinder if the corrosiveness of the water is constant. In town supply reticulated water systems the chemical make up of the water is not constant and corrosiveness varies with the changing chemical additions to the water. Aluminium sulphate, often used in water clarification, increases the corrosiveness of a water without any change in pH. Some types of black plastic pipe can cause a water to become acidic and increase the corrosiveness of the water.
An open fire! can increase the corrosiveness of a roof caught water. Hard waters are mostly not corrosive.
A corrosive index between 0 and .5 is normal.
Levels greater than 1 are associated with the, tell tale, blue or green staining caused by copper corrosion. Sea water has a corrosive index of 35
Nitrate..mg/l as N. Is a contaminant found in bore waters. This results almost entirely from fertiliser leaching into the ground water. Nitrate is rarely seen in roof caught water. Failure of septic systems will also elevate nitrate levels, this is rare and is associated with an elevated faecal content. A limit of 11 maximum has been in use for several years. High levels have been associated with a syndrome known as blue baby disease. levels less than 1 are expected.
Phosphorus.. mg/l as P. Is a contaminant also from fertiliser or industrial sources. The presences of phosphate indicates a high potential for green algae to flourish. Some cleaning agents contains significant phosphate levels. levels less than 0.1 mg/l are expected
Potassium.. Is found in high concentrations is sea water. Bore close to the ocean sometimes show elevated potassium, this is always associated with a rise in the sodium and chloride levels. Elevated potassium levels often result in increased algal growth, when exposed to light.
Levels unto 2.0 mg/l are common.
Levels between 10 and 20 are found in bores waters.
Sodium / Chloride Indicator of sea water contamination. Chlorine is often used to sanitise domestic waters and during this process the some of the chlorine is converted to chloride. Rain waters commonly have less than 5 mg/l. Inland fast flowing streams, bores and springs often have levels between 10 and 20 mg/l. Coastal situation can range from 20 to several hundred when sea water intrudes into underground aquifers. Soda waters are characterised by an increased sodium and a normal chloride.
Levels unto 50 are normal.
Levels above 100 mg/l begin to indicate the sea water presence.
Calcium / Magnesium.. are found in high quantities in limestone and dolomite and is common in bore waters from areas containing these rocks. These minerals give the water a hardness or poor foaming ability. Scaling in the kettle and hot water cylinder are common. Hard water's tend not to be corrosive.
Levels less than 10mg/l for calcium and 2 mg/l for magnesium are common.
Iron / manganese.. These metals are common in rock and often find there way into ground water. The iron is often present as iron carbonate which reacts with oxygen in the air after it is pumped out of the ground to form iron oxide (RUST). This iron oxide forms solid particles and will separate from the water. Oxidation and filtration are common methods used for the removal of iron from water. Rusty brown staining is due to iron. Black staining is due to manganese. Domestic bleaches can often assist in staining, if iron or manganese is present. From the health point of view these metals are not harmful.
Iron is a problem at levels greater than 1mg/l. levels greater than 5 can cause problems if it is used for irrigation. Levels up to 5 mg/l are most common levels over 50 have been recorded. Manganese levels are a problem above 0.5 mg/l and produce a black stain. Levels upto 5 are found naturallyThe NZ Drinking water standard recommends less than 0.2 mg fe /l.
Copper /Zinc. These metals are common in plumbing fittings such as galvanised roofing, guttering and tanks and copper pipes and hot water cylinders. Brass fittings contain both copper and zinc. Natural levels are very low compared to the levels found in corrosive situations. Copper levels of 1 give water a very bitter taste, this is often more noticeable from the hot tap due to increased cylinder corrosion at higher temperatures.
Copper levels less than 1ppm account for 95% of waters tested for copper. Zinc levels less than 1 ppm are common. Levels up to 25 ppm are associated with corrosion of plumbing fittings.
Microbiology
This examination is for determining the Sanitary quality of the water. Indicator organisms are tested rather than pathogens ( disease causing organisms) The indicators indicate the probable potential for,. ie The presence of faecal coliforms indicates faecal contamination and therefore is associated with a higher probability of the Giardia organism which is more common in faecal contaminated waters. Coliform organisms are detected using the membrane filtration technique and reported per 100ml of sample. Two plate counts are performed using a general media and incubated at 20 and 35 oC. These indicate the general background bacteria and indicate the likely presence of organisms which are likely to cause odours, bad tastes or visual cloudiness. Most waters can be effectively sanitised.
Total Coliforms. These organism’s are common in soil and often indicate soil contamination of roof caught waters or bore heads. The total coliform plate (M-Endo) grows E coli, Enterobacter cloacae, Klebsiella Pneumoniae, Salmonella typhimurium, Shegella Flexneri, proteus mirabillis
Levels less than 10 are acceptable for drinking water. Soil contamination will result in levels exceeding 1000
Faecal Coliform’s indicate the presence of faecal matter and therefore the probability of other pathogenic organisms with infection associated with faecal contact. eg. Giardia, Campylobacter. The faecal coliform plate grows E-Coli, Enterobacter aerogenes, Shigella flexneri and Salmonella typhimurim.
Levels less than 2 are acceptable for drinking water. For recreation levels up to 200 are OK
Human faecal matter is a greater risk generally than ruminant species such as sheep or cattle.
The aerobic plate count indicates the total live heterotrophic bacterial population. Two temperatures are used to indicate temperature sensitivity. Iron bacteria and many plant decay bacteria, give an increase in the 20 oC incubation and the sulphur bacteria grow equally well at both tempeatures. bacteria growing at 37 will survive in humans.
Cost including GST
Full Domestic analysis $170, Microbiology only $62, Basic potable test $75.00, Chemistry only $110, Hydroponic $85