How Is a Water Analysis Done? Which Values Are Looked At?

Most people who buy a water purifier never have their water measured before deciding. Models are researched, prices compared, offers looked at — yet what is actually in the water the system will treat remains unknown. The result is usually the same: a drinking water unit is bought for a limescale problem, or money is spent on a stage that was never needed. Yet the right decision has only one solid basis: a water analysis.

Water looking clear says nothing about the dissolved substances in it. The calcium that forms limescale, the iron that leaves stains and the chlorine that spoils the taste are all invisible. In this guide we take up step by step how to have your water tested, which values are looked at, why taking the sample correctly is critical, and how to read the report.

What Is a Water Analysis and Why Is It Needed?

A water analysis is the measurement of the physical, chemical and microbiological properties of a water sample. Parameters such as hardness, conductivity, pH, iron, manganese and microbiological load are established. That measurement reveals the real profile of the water and bases the choice of treatment on data rather than guesswork.

A water analysis is really a diagnosis. Just as a doctor does not prescribe without tests, the right treatment system cannot be chosen without knowing what is in the water. Even the water of two neighbours in the same area can come out differently; the building’s tank, the plumbing material and the depth of a well all change the picture.

An analysis brings three concrete benefits. The first is choosing the right system: which stages are needed becomes clear. The second is cost control; unnecessary stages are left out. The third is the ability to follow up: measurements taken after installation confirm that the system is genuinely working.

The importance of testing domestic water is stressed in official sources too; the US Environmental Protection Agency’s guide to testing drinking water at home states that households using a private well in particular have to monitor their own water quality. In short, a water analysis is the first step of the treatment journey — not the last.

Why Does the Need for Analysis Differ Between Mains and Well Water?

On mains water the authority measures regularly; but after the water enters a building it can be affected by the tank and the plumbing. On well water there is no public monitoring and all the responsibility rests with the user. In households using a well, therefore, a water analysis is not a preference but a basic requirement.

The difference between the two sources is about where the responsibility lies:

Even on mains water an analysis is not pointless; the published figures are a regional average and may not represent the water running from your own tap. In buildings with storage tanks and old plumbing in particular, the quality at source and the quality at the tap can differ.

On the well side the picture is clearer: without an analysis nothing is known. We took up in detail which problem in well water is removed by which stage in our article on treatment stages for well water ; but the start of that chain, too, is the water analysis result.

The Basic Parameters Measured in a Water Analysis

A water analysis generally measures hardness, conductivity and TDS, pH, turbidity, iron, manganese, chloride, sulphate, nitrate and microbiological load. Each parameter points to a different problem. Read together, these values reveal the profile of the water and the treatment stages needed.

Knowing the parameters one by one also makes the report easier to read:

For the official limit values of these parameters, the relevant regulations and an accredited laboratory report are what count. The aim in this article is to show what each value tells you; the exact thresholds are set by the reference ranges in your report.

Conductivity and TDS confuse people in particular; we took up in detail what they tell you and what they do not in our article on TDS . When those two values are read together in a water analysis report, a sound picture of the water’s mineral load emerges.

Figure 1: Water analysis parameters and the measurement process

What Do the Physical Signs Tell You?

Marks on taps and surfaces give the first clue as to which parameter may be a problem. White limescale points to hardness, red-brown staining to iron, black staining to manganese. These signs are a guide, but a water analysis must be carried out for a definite answer.

The table below matches the sign you observe with the parameter to be measured:

This table is not a diagnostic tool but a first pointer. The signs show which parameters to focus on; the exact content emerges only from a laboratory water analysis. Parameters such as microbiological load and nitrate in particular may give no visible sign at all.

How Is a Sample Taken?

A correct sample is the precondition of a correct result. A clean container should be used, the tap should be run for a while, and the inside of the container and cap should not be touched. The sample should reach the laboratory without delay. A microbiological analysis calls for a separate, sterile container.

A sample taken wrongly produces a wrong result even in the best laboratory. The steps for taking a sample correctly are these:

1. Prepare a suitable container

   Use a clean container suitable for sampling. Bottles with detergent residue spoil the result.

2. Run the tap for a while

   Run it so that the water standing in the plumbing is cleared; the sample then represents the real mains water.

3. Remove any attachments

   Filters and fittings on the tap spout can affect the sample; remove them if possible.

4. Fill without touching

   Do not touch the mouth of the container or the inside of the cap; avoid the risk of outside contamination.

5. Record the details

   The point, date and time the sample was taken should be noted; the report is interpreted with that information.

6. Deliver it without delay

   The sooner the sample reaches the laboratory, the more reliable the result; that is critical for microbiological tests in particular.

A separate procedure applies to a microbiological water analysis: a sterile container is used, the sample is never transferred to another container, and it is delivered as quickly as possible with the cold chain maintained. A sample taken for chemical analysis cannot be used for a microbiological test.

These details may look like a nuisance, but they determine the result directly. A water analysis report based on a faulty sample can show you a problem you do not have, or hide one you do.

Which Method Is Used? Field Kits Versus the Laboratory

Field kits and digital meters give a quick idea; they show basic parameters such as hardness and TDS on the spot. For a comprehensive and official result, a water analysis at an accredited laboratory is needed. The two are not rivals but complementary tools.

The roles of the two methods separate clearly:

In practice the most efficient approach is to use both. You establish the profile of your water clearly once with a comprehensive laboratory water analysis, then follow it regularly with field measurements. To watch hardness at home, a limescale test kit is used; to follow dissolved solids, a TDS meter serves the same purpose.

But it has to be said honestly: a field kit does not replace a water analysis report. Critical parameters such as heavy metals, nitrate and microbiological load are measured reliably only under laboratory conditions.

How Is a Water Analysis Report Read?

In the report each parameter is given with the measured value, the unit and a reference range. Units are generally shown as mg/L, ppm, µS/cm or °Fr. Correct interpretation calls for looking not at a single value but at the parameters as a whole; the values should be read in relation to one another.

Three things matter when reading a water analysis report. The first is the unit: the same parameter can be given in different units, and that has to be borne in mind when comparing. The second is the reference range; the range stated in the report is defined by the relevant regulations and the laboratory’s method. The third is reading it as a whole.

Why does reading it as a whole matter? Because the parameters affect one another. A high TDS value on its own, for example, does not tell you what to do; whether that load comes from hardness or from salinity is understood together with the hardness and chloride values. Equally, pH is interpreted in a corrosion assessment not on its own but together with conductivity.

Reading your report together with a specialist is the most practical route. The same water analysis result can point to different solutions depending on the intended use: the quality needed for drinking water and the quality needed for boiler feed water are not the same. We took up how that distinction is made on the industrial side in our process water article .

What Treatment Solution Does the Analysis Result Point To?

Each parameter points to a particular solution: hardness to softening, turbidity and sediment to filtration, odour and chlorine to activated carbon, high TDS to reverse osmosis, microbiological load to UV (ultraviolet) treatment, and iron and manganese to filtration with oxidation. The water analysis is the map of that matching.

The table below matches the finding in the report with the right stage:

This table is the bridge between the water analysis and the solution. Where a hardness problem is found, we took up which type and capacity of softening is needed in our softening selection guide . Where a high dissolved solids load is involved, the reverse osmosis solutions come into play.

Where a microbiological load is found, a separate stage is needed; we set out honestly how that technology works, and what it does and does not do, in our ultraviolet treatment article .

One point is worth stressing: on most waters more than one row applies at once. The solution is then not a single unit but a chain of stages. The order and capacity of those stages, again, is established from the water analysis data.

Figure 2: Taking a sample and assessing the water analysis report

How Often Should You Have a Water Analysis Done?

There is no fixed period; the frequency is set by the conditions of use. On well water, regular monitoring is recommended. On mains water, the analysis should be repeated when there is a change in taste, odour or appearance, after a change to the plumbing, or before moving to a new system.

The typical situations that call for repeating an analysis are these:

• A change in taste, odour or colour: Any sensory change in the water can point to a change in its content.
• Seasonal transitions: In well water, rainfall and the groundwater level can change the content.
• Activity in the area: Where there is excavation, construction or intensive agriculture nearby, a check is needed.
• A change of plumbing or tank: New plumbing and a new tank can affect water quality.
• Before and after installing a system: Before installation for diagnosis, afterwards for verification.
• A fall in the unit’s performance: Where the expected result is not obtained, a fresh measurement is needed.

Regular water analysis matters particularly for households using a well, because the content of groundwater can change over time and that change often gives no sign at all. On the mains side, unless something triggers it, less frequent monitoring may be enough.

After the Analysis: How Is the System Engineered?

The right system is engineered from three pieces of data: the water analysis result, the flow requirement and the intended use. The analysis establishes which stages are needed, the flow the capacity, and the intended use the quality aimed for. A choice made without those three rests, at best, on guesswork.

The process runs on this logic. First the analysis report is read and the problem parameters listed. Then the stage needed for each parameter is established. Then those stages are arranged in the right order, because the order affects efficiency directly — a membrane stage installed without pre-filtration ahead of it, for instance, blocks within a short time.

The third step is capacity. The same stage build is installed at a different scale in a kitchen producing a few litres of drinking water a day and in a business running continuously. The flow and the intensity of use determine the size of the equipment.

The last step is the intended use. Drinking water, general household water and production water carry different quality targets. The same water analysis report can point to three different solutions for those three purposes. Before “which unit should I buy”, therefore, the question “where will I use this water” has to be answered.

When those three pieces of data come together, the system is built on calculation rather than guesswork. We took up all the unit selection criteria unit selection guide step by step; but the starting point of that guide, too, is the water analysis result.

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