Why Is The TDS From My Reverse Osmosis High?

TDS, or Total Dissolved Solids, is an important measurement of water quality. Reverse osmosis systems are designed to remove a large amount of bacteria and organic contaminants from drinking water. However, when the TDS levels in your reverse osmosis system increase too high, it can be a sign that something is wrong with your system. High Total Dissolved Solids (TDS) readings in these systems can be caused by a variety of factors, from user error to equipment malfunction.

What Is TDS?

What Is TDS

Total Dissolved Solids (TDS) is a measure of the combined total of all inorganic and organic particulates suspended in water. It includes minerals, salts, and metals that have dissolved into the water after coming into contact with rocks and soil. TDS levels are measured in parts per million (ppm).

What Should Be TDS In RO?

What Should Be TDS In RO
Checking TDS In RO

The Total Dissolved Solids (TDS) that are present in water coming out of a reverse osmosis system should be very low. Depending on the type and quality of membrane used, TDS levels should generally range between 1-10 parts per million (ppm). Higher than normal TDS readings can indicate a problem with the membrane, such as clogging or fouling due to a buildup of minerals and other substances. If the TDS in your reverse osmosis system is higher than normal, you may need to clean or replace the system’s membrane. You should also make sure that the water pressure is adequate, as this can have an effect on TDS levels.

Why Is The TDS From My Reverse Osmosis High?

Dirty filter
Dirty filter of RO

Dirty filter: The most common cause of a high TDS reading is dirty filters. The membrane filter on the reverse osmosis system should be replaced every 6-12 months depending on usage, and the carbon pre-filter should be changed at least twice a year.

Low incoming water pressure
Checking water pressure

Low incoming water pressure: Another potential cause of elevated TDS levels is low incoming water pressure. If the tap water enters the RO unit too slowly, it will cause a decrease in performance of the membrane filter and lead to higher TDS levels.

Unregulated pressure: Reverse osmosis systems rely on a certain amount of pressure to be able to do its job. Without adequate pressure, the system will not be able to produce any water with acceptable levels of total dissolved solids (TDS). If this is the case, it’s likely that there is an issue with your incoming water pressure or the tankless booster pump is not running properly.

Poor quality water: A high TDS reading in a reverse osmosis system can be caused by poor quality water coming into the unit. Water that contains a high concentration of minerals, such as calcium and magnesium, can reduce the efficiency of the membrane and will cause the TDS to rise. It is important to test the feed water before installing an RO system to ensure it meets the minimum requirements.

Untreated water: Another cause of a high TDS in a reverse osmosis system is untreated water entering the unit either through bypassing the pre-filters or due to lack of maintenance on the filters. To avoid this, regular maintenance must be performed and all pre-filters should be replaced as needed. This will ensure that all incoming water is free of contaminants and fine sediment which could cause the TDS to rise.

High temperature
High temperature

High temperature: If the water temperature is high, it can cause higher TDS readings. To fix this issue, you need to reduce the incoming water temperature.

Scale buildup: Scale buildup in your reverse osmosis system can cause higher TDS readings. To fix this problem, you need to regularly descale and clean your reverse osmosis system.

Change In Water Source’s Quality: If the water source connected to your reverse osmosis system has a higher than normal TDS, then that could be causing the high readings on the product. This can occur if there is a change in the quality of the water being supplied, such as during droughts or when seasonal changes cause an increased amount of dissolved solids in the water. It is always a good idea to test your source water for TDS periodically and compare it to the output of your RO system. If there is a significant difference, then you should consider changing out the filters in your system more frequently or upgrading to better quality components.

Organic particles
Organic particles in water

Organic particles: Organic particles from the water supply can lead to a high TDS reading. These particles are often too small for conventional filters to remove and may need additional pretreatment such as carbon or sediment filtration before going into the reverse osmosis system. Debris on the membrane surface or in the tanks of the reverse osmosis system can also lead to a high TDS reading.

Post-Filter Is Adding Minerals To The Water: One of the most common causes of high TDS readings from a reverse osmosis (RO) system is post-filter mineralization. Post-filter mineralization occurs when minerals are added to the water after it has gone through the RO membrane, and before it enters your tap. This is done by adding a post-filtration device, such as a carbon or mineral filter. When this happens, the previously filtered water is now enriched with minerals and therefore has a higher TDS reading than before it passed through the post-filter.

Re-Using Rejected Water: Rejected water from a reverse osmosis (RO) system contains high levels of total dissolved solids. This water can be used for other purposes such as irrigation or flushing toilets, but some homeowners prefer not to re-use it due to its high TDS level. It is important to remember that this water does still contain potable water and can be used for other purposes.

Faulty RO Membrane
RO Membrane

Faulty RO Membrane: The reverse osmosis membrane is a crucial component of the RO system and plays a major role in controlling total dissolved solids levels. It is responsible for removing up to 99% of minerals, salts, organic matter, heavy metals, and other contaminants that could be entering your drinking water. If the membrane has become faulty or damaged, it can result in higher TDS levels. To check if the membrane is the source of high TDS, replace it with a new one and run a test to measure TDS levels. If the TDS levels are still high, further investigation may be needed. Other possible sources of high TDS could include poor quality water supply, clogged filters, and leaking faucets or pipes.

TDS Creep Causing Incorrect Testing: Sometimes, the TDS reading on your reverse osmosis system can be higher than expected due to a phenomenon called “TDS creep”. This is when particles from dirt, debris, or scale build up in the membrane housing and are not flushed out properly during bi-annual maintenance. This buildup of particles affects the accuracy of the TDS testing, making it seem as though the water is higher in contaminants than it actually is. To remedy this issue, a full replacement of the membrane housing and filter cartridge should be performed to remove any built-up dirt or scale.

Why Is TDS So High After Changing The RO?

Why Is TDS So High After Changing The RO
Changing The RO

High TDS (Total Dissolved Solids) levels after a reverse osmosis filter change could be caused by several factors. Common causes of high TDS are: bacterial growth, decaying organic matter, and heavy mineral deposits in the water.

When the membrane has been replaced, it may not be as effective at removing dissolved solids as it was before. This could be due to a manufacturing defect, the water having higher levels of dissolved solids than normal, or high levels of particulate matter in the water that clogs the membrane, preventing it from working effectively.

How To Measure TDS In Water?

Filter paper
Filter paper to measure the TDS in water.

Filter paper: You can use a filter paper to measure the TDS in your water. In this method, you soak a piece of filter paper in the RO or other water sample and wait for it to dry completely. The TDS is then determined by measuring the amount of mineral residue left on the paper after drying.

Digital TDS meter
Digital TDS meter

Digital TDS meter: The digital TDS meter is an important tool when it comes to determining the TDS level of your reverse osmosis filter. The meter measures the total dissolved solids in water and gives you a reading in parts-per-million (ppm). The higher the ppm, the more solid particles are present in the water. A high TDS reading could be an indication of a broken or clogged filter. If the filter is not working properly, it may not be able to remove enough contaminants and therefore TDS levels can rise.

How To Reduce The TDS From Water?

How To Reduce The TDS From Water
Reducing The TDS From Water

Reducing the Total Dissolved Solids (TDS) from water can be a challenging process, especially if you are using Reverse Osmosis (RO).

  • Ensure that your RO system is properly set up and maintained. A faulty membrane or system can lead to higher TDS readings. Additionally, if you have an older system, consider replacing the filters and membranes with new ones as they may become less effective over time.
  • Check your feed water pressure to ensure it is in line with the manufacturer’s specifications. If the pressure is too high, the system may not be able to effectively remove TDS from the water.

Why Do You Need To Measure Total Dissolved Solids?

Taste: Total dissolved solids, or TDS for short, are a measure of the combined content of all inorganic and organic substances contained in a liquid. High levels of TDS can affect the taste of water due to the compounds present which can make it brackish, salty, or otherwise unpleasant.

Health Purposes: Reverse oosis systems can remove a variety of contaminants from water, providing improved quality for drinking, cooking and other purposes. High levels of total dissolved solids (TDS) in the water are usually caused by high mineral content in your source water. This is often referred to as “hard” water. Depending on the type of filtration used in your reverse osmosis system, high TDS levels may not be completely removed.

Maintenance of Filters: It is important to regularly maintain and replace reverse osmosis filters, as they are designed to purify the water of harmful contaminants. If your filter cartridges become clogged with sediment, it can cause a buildup of pressure in the system which can result in higher than normal TDS levels. To avoid this, you should make sure to change out your filters regularly, as recommended in the manual for your specific RO system.

Cooking: Reverse osmosis water can be used in many ways – from making coffee to cooking. But it’s important to remember that, although the water may seem clean and fresh, it can still contain high levels of total dissolved solids (TDS). Because these particles are too small for filters to catch, the TDS level will remain higher than that tap water. To ensure the safety and quality of food cooked with reverse osmosis water, it’s important to check the TDS level regularly and adjust accordingly. If your TDS is too high for cooking purposes, you may need to use a different water source or pre-treat the RO water before using it in food preparation.

Plumbing and Appliances: High TDS levels can cause damage to plumbing and appliances that use reverse osmosis water. A high TDS level will increase the mineral content of your water, which can lead to sediment build-up in pipes, boilers or other fixtures. This build-up can result in damage or reduced efficiency of your equipment, so it’s important to check the TDS level regularly and adjust accordingly. If your TDS is too high, you may need to reduce the amount of reverse osmosis water used in plumbing and appliances or pre-treat it before use.


What is the best TDS level for fish tank?

What is the best TDS level for fish tank
TDS level for fish tank

The ideal Total Dissolved Solids (TDS) levels for a fish tank vary depending on the type of species you are looking to keep. Generally, most tropical freshwater fish tanks should have TDS levels between 0-50 parts per million (ppm). Marine aquariums can range from 0-400 ppm, however for optimal health and welfare of the fish, it should not go over 100 ppm.

Can a reverse osmosis membrane handle 6000 TDS?

RO Membrane
RO Membrane

Reverse osmosis membranes can handle up to 6000 total dissolved solids (TDS) with proper pre-treatment. Pre-treatment of water with a sediment filter and/or granular activated carbon filter, before it reaches the reverse osmosis membrane, can help reduce TDS levels significantly. In some cases, an additional filter such as a carbon block filter can also be beneficial. Proper maintenance of the system, including regular membrane cleaning and replacement, is important in keeping TDS levels from rising too high.

Can I increase the TDS of RO?

Can I increase the TDS of RO
Increase the TDS of RO

Yes, you can increase the TDS of reverse osmosis (RO) water by using a remineralization filter. This type of filter adds beneficial minerals like calcium and magnesium back into the filtered water, making it more alkaline and increasing its total dissolved solids (TDS). It also helps improve taste and smell as well as provide a mineral source for beneficial bacteria in the aquarium. Remineralization filters are typically simple to install and require no maintenance or ongoing costs.

Is low TDS water harmful to Human Body?

No, low TDS water is not harmful to the human body. However, it can cause mineral deficiencies if consumed regularly and in large amounts over a long period of time. Therefore, it is important that adequate concentrations of essential minerals are supplemented back into the water before consumption. This is possible by adding a remineralization filter or supplementing minerals directly into the water. Low TDS water can also cause digestive issues if consumed in large amounts and may lead to dehydration due to its high osmotic pressure, which draws out moisture from cells.


the high TDS reading can be caused by various factors, such as the quality of water used in the system, tank age, and level of mineral content. It is important to determine the cause in order to take corrective action to reduce TDS levels. If necessary, replacing the membrane or flushing the tank may help reduce the TDS level. Additionally, regular maintenance is key to ensuring your reverse osmosis system is running safely and efficiently.

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