Water analysis
Water analysis is carried out on different types of water, drinking water, groundwater, surface water and wastewater. For horticulturists and farmers, it can be raw water or finished nutrient solutions.
A water analysis is an examination of the water sample to find out its chemical and physical properties. This is done to examine whether the water is fit to drink, to check that it complies with legal limits for different parameters, or to examine how the water is affected by different factors such as wastewater or algal blooms. A water analysis may include measurements of parameters such as pH, alkalinity, plant nutrients, chemical oxygen demand (COD-Mn), chloride and many others.
Scope of the water analysis
Our water analysis includes pH, conductivity, nitrate nitrogen, ammonium nitrogen, phosphorus, potassium, magnesium, sulfur, calcium, manganese, boron, copper, iron, zinc, molybdenum, silicon, sodium, aluminum and from 01/03/2024 chloride is again included in the analysis.
Water analysis for growers
Take water samples on raw water for irrigation or on finished nutrient solutions.
Raw water for nutrient irrigation
Water analysis is performed with the addition ofalkalinity(bicarbonate content, buffering capacity of water) to calculate how to adjust the pH in the fertilizer recipe (see more information further down the page).
Growing with drip irrigation outdoors
Take samples of the nutrient solution to check that the nutrient composition of the solution is correct. Supplement with spurway analysis on the soil.
Cultivation in substrate
Sample both the outgoing nutrient solution and the water drained from the substrate (drainage water), or press water from the substrate. Sampling in substrate culture with nutrient solution is repeated every two weeks for continuous adjustment of fertilization.
Especially when circulating nutrient water, water analysis is an important tool to continuously adjust fertilization. This allows the grower to optimize nutrient composition and control irrigation to avoid accumulation of substances that the plant does not consume much of. Precision fertilization gives better results in terms of production, quality and the environment. And with the right nutrients applied, the bottom line is better!
Drinking water from your own well
Analyze drinking water to determine if it is safe to drink. If it contains elevated levels of certain plant nutrients, this is a sign of organic pollution from sewage or animal husbandry. However, if the levels of plant nutrients are below the Swedish Food Agency's limits, the water is of good quality and further analysis should not be necessary. If the water is to be drunk by children under 7 years of age, fluoride should also be analyzed in addition to our standard analysis.
To find out what the different limits for drinking water from your own well mean, see the attached link on the Swedish Food Agency's website:
Optional Alkalinity
If the water is raw water to be used for nutrient solution, request additional analysis of alkalinity. Alkalinity is the buffering capacity or hydrogen carbonate ion content of the water, (HCO3-).
If the alkalinity is above 100 mg/l, acid needs to be added to convert the carbonates into carbon dioxide, so that the alkalinity is adjusted down to 50 mg/l. More than this must not be removed, as the pH will become unstable and may be too low.
Example: If the water has an alkalinity of 280 mg/l, you want to neutralize 280-50=230 mg/l. Multiply the amount of acid to be added according to the table below by 230/100. If 62% nitric acid is to be used, then 0.12 x 230/100 = 0.276 liters of nitric acid per 1000 l of irrigation water. Read more...
To neutralize 100 mg/l of HCO3- per 1000 litres of irrigation water, the following amount of acid is required:
| Acid product | per 1000 l of irrigation water | per 100 l stock solution with 1:100 dilution |
| Phosphoric acid 85% | 0,10 liter | 1.0 liter |
| Phosphoric acid 75% | 0.125 liters | 1.25 liters |
| Magnofoss | 0,17 liter | 1.7 liters |
| Nitric acid 62% | 0,12 liter | 1.2 liters |
| Nitric acid 53% | 0.145 liters | 1.45 liters |
Other water analyses
COD-Mn Chemical oxygen demand (Chemical oxygen demand)
The chemical oxygen demand of water is a measure of the amount of oxygen required to break down the organic matter in the water. An elevated oxygen demand is an indication of undegraded organic matter in the water and can lead to the growth of micro-organisms. In irrigation water, COD-Mn should be below 4 mg/l.
TOC Total organic carbon
Total organic carbon content of the water, both dissolved and particulate. A level of 4-8 mg/l is considered low.
Total phosphorus (Tot-P)
The total phosphorus content of the water, both organic and inorganic, dissolved and particulate. This analysis is applied to surface waters to assess water quality.
Phosphate phosphorus
The dissolved inorganic phosphorus content of water. The form of phosphorus that is directly available for plants and microorganisms to take up. As phosphorus is often the limiting factor for growth in aquatic environments, it causes, for example, algal blooms.
Suspended matter
The particulate content of water, often caused by erosion associated with rainfall and high water flows.
We can also help with other water analyses. Contact us for more information!
Samples for environmental analysis from freshwater and wastewater may need to be taken in special sample bottles. Order sampling bottles from us!
Bacterial analysis
We forward samples for bacterial analysis to another laboratory. Always contact us before sampling for instructions and sterile packaging for the samples. For analysis of bacteria in well water read more here...
Sampling instructions water analysis
The LMI provides 250 ml sampling bottles for this purpose.
Tap water
Let the water run for 10 minutes to ensure that the water is fresh and free of impurities in the water pipe.
Cultivation substrate
Take samples from several different places in the culture. In case of repeated sampling, take the samples in the same aisles/rows. Use clean sampling equipment (syringes/presses if necessary).
Nutritional solutions
A well rinsed PET bottle works just as well. Rinse the bottle a few times with the water to be sampled.
The sample should be representative of the water to be analyzed. Fill the bottle to the top so that no air is left. In case of multiple samples, label the samples with the sample number. Attach the delivery note as below. If the sample is not delivered to the laboratory immediately, it should be stored in a refrigerator.
Submission of samples
Some analyses must be carried out within a short time:
- pH, COD-Mn, nitrate and ammonium and suspended solids shall be analyzed within 24 hours.
- Phosphate-phosphorus should be submitted immediately to be filtered within 4 hours.
- Bacterial analysis must be passed on to another laboratory on the same day as the sample was taken. Submission no later than 13.30 on weekdays (except the day before red day, when we do not accept bacterial samples). We do not accept samples for bacterial analysis by post.
By submitting samples, you agree to the analysis being carried out even if delivery to the laboratory takes more than 24 hours.
Consignment note
Attach the delivery note with the sample number/sample name. Remember to include the name and billing details (including organization/personal number), as well as the e-mail address of the persons to whom we will send the results. To delivery notes...
Download the delivery note!
Response time
Results of mineral analysis of drinking water and nutrient solutions are submitted by e-mailmail the day after the sample reaches the LMI, or the same day if the samples are submitted by 09:30.
Other analyses take about 10 working days.
