Understanding your results
Water parameter library
Every result on your certificate is explained here in plain English: what the parameter is, where it comes from, why it matters, and what a Pozzani engineer can do if a result is over the guideline.
- Aluminium µg/l A metal from soils and from some treatment chemicals. Causes discolouration; the guideline is set for appearance. Read the guide →
- Ammonium mg/l Also called ammonia. Usually a sign of sewage or farm waste reaching the supply, or of bacterial activity. Read the guide →
- Antimony µg/l A metal that can leach from some solders and fittings. Tested for new-build compliance in Scotland. Read the guide →
- Arsenic µg/l A naturally occurring element in some rocks and soils. A health parameter with a low guideline. Read the guide →
- Boron mg/l An element from natural minerals and some detergents. Tested for new-build compliance in Scotland. Read the guide →
- Cadmium µg/l A toxic metal from galvanised pipework, industrial pollution and some fertilisers. Tested for new-build compliance in Scotland. Read the guide →
- Calcium mg/l One of the two minerals that make water hard. Not a health concern. Read the guide →
- Chloride mg/l Dissolved salt. High levels taste salty and can point to seawater, road salt or sewage reaching the supply. Read the guide →
- Chromium µg/l An industrial metal. Rare in private supplies; tested for new-build compliance in Scotland. Read the guide →
- Clostridium perfringens (incl. spores) cfu/100ml A hardy faecal indicator whose spores survive for months. Shows contamination may have happened some time ago. Read the guide →
- Cobalt µg/l A trace element plants need in tiny amounts. Measured for hydroponics; no UK drinking-water limit. Read the guide →
- Coliform bacteria cfu/100ml A family of bacteria used as a general warning sign that a supply is not properly protected or treated. Read the guide →
- Colony count 22°C cfu/ml A count of the general bacteria in the water. There is no fixed limit; what matters is a sudden change. Read the guide →
- Colony count 37°C cfu/ml A count of bacteria that grow at body temperature. Watched for change alongside the 22°C count. Read the guide →
- Conductivity µS/cm A quick measure of how much dissolved mineral the water carries overall. Read the guide →
- Copper mg/l A metal that dissolves from copper pipework, especially in soft or acidic water. Causes blue-green staining. Read the guide →
- E. coli cfu/100ml A bacterium found in the gut of people and animals. Finding it means the water has been contaminated with faeces and is not safe to drink untreated. Read the guide →
- Enterococci cfu/100ml A second indicator of faecal contamination that survives longer in water than E. coli. Read the guide →
- Fluoride mg/l Naturally present in some groundwaters. Protects teeth at low levels; too much can mottle them. Read the guide →
- Hardness mg/l CaCO3 The amount of calcium and magnesium in the water. Causes limescale but is not a health concern. Read the guide →
- Iron µg/l A common metal in groundwater. Causes orange-brown staining and a metallic taste rather than any health risk. Read the guide →
- Lead µg/l A metal that gets into water from old pipes and fittings. There is no safe level, so the aim is as little as possible. Read the guide →
- Legionella spp. cfu/l Bacteria that grow in warm water systems and can cause Legionnaires' disease when inhaled in fine spray. Read the guide →
- Magnesium mg/l The second hardness mineral. Not a health concern; reported so the mineral balance can be read. Read the guide →
- Manganese µg/l A metal often found with iron. Causes black staining and a bitter taste; the guideline also reflects a health consideration at high levels. Read the guide →
- Mercury µg/l A toxic metal, rare in UK water. Tested where there is reason to suspect industrial or mining pollution. Read the guide →
- Molybdenum µg/l A trace element essential to plants for using nitrogen. Measured for hydroponics; no UK drinking-water limit. Read the guide →
- Nitrate mg/l A nutrient that reaches water from fertilisers, manure and septic systems. Matters most for bottle-fed babies. Read the guide →
- Nitrite mg/l A short-lived form of nitrogen that signals contamination or incomplete treatment. Matters most for bottle-fed babies. Read the guide →
- Odour dilution number How the water smells, assessed by the laboratory. Should be acceptable with no abnormal change. Read the guide →
- pH pH units How acidic or alkaline the water is. Low pH water is corrosive and dissolves metals from pipes. Read the guide →
- Phosphate mg/l A plant nutrient. No drinking-water limit; measured for hydroponics to balance the feed. Read the guide →
- Pseudomonas aeruginosa cfu/250ml An opportunistic bacterium that thrives in warm water, hoses and biofilm. A key check for pools, spa pools and vulnerable users. Read the guide →
- Silica mg/l Dissolved silica from rocks and sand. Relevant to hydroponic nutrient balance and to scale on equipment. Read the guide →
- Sodium mg/l The other half of salt. Raised naturally in some areas and by water softeners. Read the guide →
- Sulphate mg/l A natural mineral. High levels taste bitter and can have a laxative effect for people not used to them. Read the guide →
- Taste dilution number How the water tastes, assessed by the laboratory. Should be acceptable with no abnormal change. Read the guide →
- Total organic carbon mg/l A measure of all the organic matter in the water. Watched for change; high levels affect disinfection. Read the guide →
- Turbidity NTU How cloudy the water is. Cloudiness can shield bacteria from disinfection and is often a sign of other problems. Read the guide →
- Zinc µg/l A metal from galvanised pipes and brass fittings. Affects taste and appearance rather than health. Read the guide →