The difference between PPM and TDS matters when a Saudi hotel, restaurant, café, office or beverage site is choosing filtration, softening or reverse osmosis. PPM (parts per million) is a unit used to express concentration. Total dissolved solids, or TDS, is the combined dissolved load in the water, usually reported in that unit. A handheld meter can estimate TDS, but it cannot tell you which substances are dissolved, or whether the water will scale your equipment.
This guide explains what the numbers mean, the ranges that matter for coffee and drinking water, how to read a result from your own site, and how to turn it into a treatment brief based on what actually reaches the equipment.
TL;DR
- PPM is a concentration unit. TDS describes the combined dissolved load reported in that unit (or in mg/L, which is numerically close in dilute water).
- A conductivity meter estimates TDS using a conversion factor, so the displayed value depends on the meter and the mix of dissolved ions.
- The Specialty Coffee Association targets around 150 ppm for brewing water, and WHO taste panels rate drinking water under 300 mg/L as excellent.
- Hardness is not the same as TDS. Calcium and magnesium drive most scale decisions, while TDS includes a broader mixture.
- Choose treatment only after combining the water chemistry with demand, flow, pressure, temperature and the outlet quality your equipment needs.
In this article
- What PPM and TDS actually mean
- Why a conductivity meter gives an estimate
- TDS ranges for coffee and drinking water
- Follow the Saudi site water route
- Read TDS beside hardness and the wider chemistry
- What high TDS does to commercial equipment
- Match the results to the treatment route
- Turn the results into a treatment brief
- Frequently asked questions
What PPM and TDS actually mean
Parts per million describes concentration. In dilute water, a result expressed as milligrams per litre is numerically close to a result expressed as PPM, so a reading of 600 ppm means roughly 600 milligrams of dissolved material in every litre. The laboratory report and method remain the authority for any result.
TDS is the combined mass of dissolved inorganic and organic material. It is not the name of one contaminant. Sodium, chloride, sulphate, bicarbonate, calcium and magnesium can all contribute to the total. When a supplier talks about "the ppm of the water", they almost always mean its TDS.
Saudi Water Authority material treats TDS, electrical conductivity, pH and hardness as separate parameters within water-quality analysis.[1] That separation is useful for buyers: two sites can record a similar TDS value while having different scale potential, taste, corrosion behaviour or treatment needs.
Dissolved minerals are not bad in themselves. Calcium and magnesium contribute to taste and mouthfeel, and WHO notes that water with very low TDS can taste flat and insipid.[2] The question for a Saudi operator is never "how do I get to zero?" but "what is the right range for each application, and how far is my supply from it?"
| Reading | What it tells the buyer | What it does not prove |
|---|---|---|
| PPM | The unit used for a concentration result | Which parameter was measured |
| TDS | The broad dissolved-solids load | The identity of each ion |
| Conductivity | How readily the water carries electrical current | A direct laboratory TDS result |
| Total hardness | Mainly calcium and magnesium scale potential | The full dissolved-solids profile |
| pH and alkalinity | Acid-base condition and buffering | Whether one treatment stage is enough |
Why a conductivity meter gives an estimate
A handheld TDS meter normally measures electrical conductivity and converts that reading into an estimated TDS value. The conversion is convenient for trend checks, but it is not universal. Different dissolved ions conduct electricity differently, temperature affects conductivity, and meters may use different factors.
US Geological Survey guidance explains that conductivity can be related to dissolved-solids concentration, but the relation should be established for the water being assessed rather than treated as one fixed conversion for every source.[3] This is why two instruments can show different TDS values from the same sample even when neither is faulty.
When you take a reading, record:
- the raw conductivity reading and its unit;
- the displayed TDS result and the meter's conversion factor;
- sample temperature or automatic temperature-compensation status;
- instrument model, calibration solution and calibration date;
- the exact point in the building and the operating condition at the time.
Use the meter to compare repeat readings from the same point and method. Use laboratory analysis where the decision depends on mineral balance, a named substance or an acceptance limit. A field meter is a consistent screening tool, not a complete specification.
TDS ranges for coffee and drinking water
Two published references give useful working targets.
| Application | Working range | Source |
|---|---|---|
| Espresso and filter coffee | Target around 150 mg/L, acceptable 75 to 250 mg/L | Specialty Coffee Association water standard[4] |
| Drinking and table water (taste) | Under 300 mg/L rated excellent, 300 to 600 mg/L good | WHO taste-panel ratings[2] |
| Drinking water (taste and usability) | 500 mg/L secondary guideline | US EPA[5] |
For ice machines, combi ovens, steam equipment and glasswashers, use the water specification in the manufacturer's installation guide. These machines heat or freeze water all day, so their limits are usually set on hardness and chloride as well as TDS.
Saudi supplies vary. Municipal water in the Kingdom comes largely from desalination, blended in many areas with treated groundwater, and published research cites Saudi drinking-water guidelines allowing TDS between 100 and 1,000 mg/L.[6] Readings at a commercial site can also change after storage tanks and booster sets. It is normal for two branches of the same restaurant group in the same city to read differently, which is why chains struggle to keep coffee consistent without treatment.
Follow the Saudi site water route
The reading that matters is the water the proposed system will treat. In a Saudi commercial building, that may not match a general supply report or a reading taken at the easiest washroom tap.
Draw the route from the incoming connection through any break tank, storage tank, booster set, pressure zone and existing treatment to the protected equipment. Mark low-use branches and any alternative supply. Saudi Water Authority guidance presents water quality as a value-chain responsibility, from production and distribution through to consumer-side use.[1]
A practical plan uses three points:
- Incoming supply: the baseline before site storage and internal distribution.
- After storage or boosting: what leaves the route used in normal operation.
- Proposed treatment inlet: the chemistry and hydraulic condition the new system must handle.
Add a point of use only when it answers another question, such as whether a long branch or an old cartridge changes the result. Do not combine locations in one bottle. Note tank level, occupancy, recent shutdowns and whether pumps were running normally.
For chemical or microbiological analysis, use a laboratory whose accredited scope covers the parameter and method you need. The Saudi Accreditation Center lists accredited bodies, but check the specific scope rather than relying on the word "accredited" alone.[7]
Read TDS beside hardness and the wider chemistry
A high or changing TDS reading justifies a closer look, but it does not automatically justify reverse osmosis. A moderate TDS value does not rule out hardness scale either.
A reading of 200 ppm made up mostly of calcium and magnesium can suit brewing well. A reading of 200 ppm dominated by chloride is a corrosion risk for boilers and espresso machines. Chloride deserves particular attention where supplies come from desalinated or brackish sources.
Choose the analysis around the application:
- Total hardness as CaCO3: for scale risk and softening decisions.
- Conductivity and TDS: for dissolved-load trends and membrane assessment.
- pH and alkalinity: for stability, buffering and treatment compatibility.
- Chloride, sulphate and sodium: for mineral balance, taste and material choices.
- Turbidity or suspended solids: where particles, tank deposits or cartridge loading are a concern.
- Residual disinfectant: where taste, carbon treatment or downstream equipment matters.
- Targeted microbiology: where the site water-safety plan raises a hygiene question needing specialist sampling.
A hotel protecting hot-water equipment needs hardness, demand and temperature. A coffee operation needs the equipment maker's water requirements as well as hardness, alkalinity and dissolved load. A beverage line may need repeatable inlet chemistry and tighter outlet targets. An office drinking-water point may focus more on taste, sediment and serviceability.
If hardness is your main question, our commercial water softener guide for Saudi Arabia goes deeper.
What high TDS does to commercial equipment
Dissolved minerals come out of solution wherever water is heated or evaporated, which is exactly what espresso machines, combi ovens, ice machines and glasswashers do all day.
The damage follows a pattern. Scale forms on heating elements and boiler walls, pushing up energy use. Flow restrictors and solenoid valves clog. Filter cartridges run out before their rated capacity, and reverse osmosis membranes foul early where pre-treatment has been skipped. Manufacturers take this seriously: La Marzocco's warranty excludes damage caused by poor water quality and scaling.[8]
Guests notice too. Water that reads too high can taste heavy, coffee can turn dull, and white deposits appear on glassware. Saudi Arabia's specialty coffee scene has raised expectations, and two branches running identical beans and machines can pour different espressos purely because of the water.
Match the results to the treatment route
Treatment should follow the measured pattern, not a preferred product.
| Result pattern | Route to assess | Checks before selection |
|---|---|---|
| Hardness is the main issue | Ion-exchange softening | Peak flow, daily demand, regeneration and continuity |
| Chlorine, taste or odour is the defined issue | Activated carbon | Contact time, flow, cartridge or media change criteria |
| Turbidity or suspended solids confirmed | Sediment or depth filtration | Particle loading, pressure loss and cleaning or backwash duty |
| Broad dissolved load must come down | Reverse osmosis | Feed chemistry, recovery, pre-treatment, storage and reject-water route |
| Hygiene risk identified | Site-specific control plan | Specialist sampling, system design and verification responsibility |
Softening swaps calcium and magnesium for sodium. It changes the mineral profile without much change to overall TDS, which matters on high-TDS Saudi supplies. Where measured hardness drives the decision, the Regal softener range covers commercial sizes to assess against flow, demand and regeneration.
Where chlorine, taste or odour is the issue, the Regent Carbon 3072 is an activated-carbon route. It should still be sized from the actual duty and outlet target.
Confirmed suspended solids may point to a depth-filtration stage such as the Regent Sediment 3072, subject to flow, pressure and loading.
Where the results support dissolved-solids reduction, the Majestic RO is a commercial membrane route to assess alongside pre-treatment, output demand and storage. RO water for coffee is then blended or remineralised back into the target band, because near-zero TDS is as much a problem for taste and equipment as high TDS. Our guide to reverse osmosis in Saudi Arabia explains how this works, and choosing between a softener, filter or RO compares the routes side by side.
These examples are not a treatment calculation. The same TDS number can lead to a different design when hardness, chloride, alkalinity, temperature or the required outlet quality changes.
Turn the results into a treatment brief
Send potential suppliers one written brief containing:
- the points in the building where readings were taken, with dates, methods and laboratory details;
- typical, minimum and maximum inlet results where available;
- the outlet quality each named piece of equipment needs;
- daily demand, peak and sustained flow;
- static and minimum running pressure;
- operating hours and how long the supply can be interrupted;
- available space, power, drainage and access;
- monitoring, consumable and maintenance expectations;
- commissioning check points and acceptance criteria.
Ask what each proposed stage changes, which inlet conditions its performance assumes, and how you will know when it stops performing. "Reduce PPM" is not a complete acceptance criterion. Say whether the target is hardness, TDS, chloride, chlorine, turbidity or another named parameter.
Commission under representative flow. Record the before and after results, instrument details, settings and first pressure readings. Those records become the baseline for maintenance and fault finding.
Frequently asked questions
1. What is the difference between PPM and TDS?
PPM is a unit of concentration. TDS is the combined dissolved-solids measurement, which may be reported in PPM or milligrams per litre.
2. What is a typical TDS level in Saudi Arabia?
It varies widely. Published research cites Saudi drinking-water guidelines allowing TDS between 100 and 1,000 mg/L. Desalinated municipal supplies can read a few hundred ppm, while blended, stored or groundwater-influenced supplies can read higher. The only reliable answer for your site is a measured one.
3. What is a good TDS level for drinking water?
WHO taste panels rate water under 300 mg/L as excellent and 300 to 600 mg/L as good. The US EPA's secondary guideline, set for taste and usability, is 500 mg/L.
4. What TDS should I use for espresso?
The Specialty Coffee Association targets around 150 mg/L, with an acceptable range of about 75 to 250 mg/L, alongside hardness and alkalinity values. Always check your machine maker's water specification as well.
5. Does a TDS meter measure every dissolved substance?
No. It normally measures conductivity and converts it into an estimate. It does not identify individual ions or contaminants.
6. Is TDS the same as hardness?
No. Hardness mainly reflects calcium and magnesium, while TDS includes a broader range of dissolved material.
7. Does a high TDS reading mean my water is unsafe?
Not by itself. TDS measures the quantity of dissolved material, not its identity. For hotels, restaurants and cafés, the immediate concerns with high TDS are equipment damage, taste and consistency between sites.
8. Does a high TDS reading mean reverse osmosis is required?
Not by itself. Confirm the dissolved profile, the outlet requirement, demand and the other treatment routes first.
9. Can a supply report replace readings from my own site?
It is a useful baseline, but it may not represent conditions after your tanks, pumps, pipework or existing treatment.
Talk to Sovereign Water about your Saudi water brief
Send us the application, a sketch of the water route, any results you have, demand, flow, pressure and the outlet quality you need. Sovereign Water can use that to recommend a treatment route, and a chargeable site survey can fill in what is missing.
Sources
[1] https://swa-cdn.swa.gov.sa/Reports/unbottled_drinking_water_quality_standards_in_the_kingdom_of_saudi_arabia_report_2025.pdf: Saudi Water Authority, Unbottled Drinking Water Quality Standards in the Kingdom of Saudi Arabia, 2025
[2] https://cdn.who.int/media/docs/default-source/wash-documents/wash-chemicals/tds.pdf: World Health Organization, Total Dissolved Solids in Drinking-water, background document
[3] https://pubs.usgs.gov/tm/09/a6.3/tm9-a6_3.pdf: US Geological Survey, Specific Conductance, Techniques and Methods 9-A6.3
[4] https://www.urbansaqua.com/wp-content/uploads/2023/09/www.urbansaqua.com-robust-ro-drinking-water-systems-water-standards.pdf: Specialty Coffee Association water standard (TDS target 150 mg/L, acceptable 75 to 250 mg/L)
[5] https://www.epa.gov/sdwa/secondary-drinking-water-standards-guidance-nuisance-chemicals: US EPA, Secondary Drinking Water Standards
[6] https://www.swcc.gov.sa/uploads/water-16-01810%20(3).pdf: Al-Hamzah and Fellows, Drinking Water Quality in the Kingdom of Saudi Arabia, Water 2024
[7] https://saac.gov.sa/en/accredited-cabs: Saudi Accreditation Center, Accredited Bodies
[8] https://www.lamarzocco.com/uk/en/warranty/: La Marzocco, warranty terms
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