Consideration of Reverse Osmosis for Household Water with TDS 500-2000

Clean water is a fundamental need for every household.

However, the quality of available water does not always meet the desired standards. One important parameter in assessing water quality is Total Dissolved Solids (TDS). When the TDS value of the water in your home is in the range of 500 to 2000 mg/L, the question often arises whether the use of a Reverse Osmosis (RO) system is the right solution. This article will take an in-depth look at the important considerations in using an RO system for household water with such TDS levels.

Understanding TDS and its Implications

Total Dissolved Solids (TDS) refers to the total amount of minerals, salts, metals, cations or anions dissolved in water. Water with high TDS is often associated with poor taste, potential scaling on equipment, and in some cases, health risks. The TDS range of 500-2000 mg/L is quite high for drinking water, considering that WHO standards recommend TDS below 600 mg/L for good drinking water.

Household water sources usually come from groundwater (wells) or PDAM water. Groundwater tends to have higher TDS due to longer contact with rocks and minerals in the soil. Meanwhile, PDAM water, although it has gone through a treatment process, sometimes still has a fairly high TDS depending on the source of the raw water.

Reverse Osmosis: An Effective Solution to Lower TDS

Reverse Osmosis (RO) is a water filtration technology that is highly effective in reducing TDS. The system uses semi-permeable membranes that are capable of filtering particles down to 0.0001 microns in size. This process not only removes minerals and salts, but is also effective in filtering out various contaminants such as bacteria, viruses, and various chemical compounds.

For water with a TDS of 500 milligrams (TDS), RO is a highly effective filtration technology.

For water with a TDS of 500-2000 mg/L, RO systems can be an excellent choice. These systems are capable of reducing TDS by 90-99%, producing water of excellent quality for consumption. However, there are several factors to consider before deciding to install an RO system in your home.

Considerations of Using RO for Household Water

1. System Efficiency and Capacity

A household RO system is generally designed to produce a certain capacity of drinking water per day. It is important to choose a system with a capacity that suits your family's needs. Keep in mind that traditional RO systems waste a large amount of water as reject water, which can be up to 3-4 times the amount of water produced. This can be a problem in areas with limited water supply.

To improve efficiency, some manufacturers have developed RO systems with water-saving technologies. For example, Pentair Merlin Undersink Reverse Osmosis offers a more efficient RO system with a lower water discharge ratio.

2. Raw Water Quality and Pretreatment

Before entering the RO system, water with high TDS may require pretreatment to prevent fouling or scaling of the RO membranes. This could involve using a softener to reduce hardness, an activated carbon filter to remove chlorine, or a sediment filter to remove coarse particles.

If the raw water contains high iron or manganese, which is often the case with well water, specialized filters such as Clack Birm Iron Removal Media or Inversand Manganese Greensand may be required. For water with high organic content, the use of Calgon Coal-based Activated Carbon can be very helpful.

3. Proper RO Membrane Selection

For water with a TDS of 500-2000 mg/L, proper RO membrane selection is critical. Brackish water RO membranes are generally suitable for this TDS range. Some options to consider include:

• DuPont FilmTec Brackish Water Membranes
• CSM Brackish Water Membranes
• Toray Brackish Water Membranes
• Toray Brackish Water Membranes

Membrane selection should consider not only TDS, but also the specific composition of the raw water and the desired flow rate.

4. Remineralization of RO Resulting Water

One of the criticisms of RO systems is that the process removes not only harmful contaminants, but also minerals that are beneficial to the body. To combat this, some modern RO systems are equipped with a remineralization stage. This could involve the use of media such as Clack Calcite and Corosex pH Adjustment Media that adds back essential minerals into the RO produced water.

5. Cost and Maintenance

The initial investment for a household RO system can be quite significant. In addition to the cost of the main unit, one also needs to consider the cost of installation, periodic filter replacement, and membrane replacement every few years. However, when compared to the long-term cost of purchasing bottled drinking water, RO systems can be a profitable investment.

Routine maintenance is essential to ensure optimal performance of the RO system. This includes replacement of pretreatment filters, membrane cleaning, and periodic system sanitization. The use of quality components such as Pentair Pentek Cartridge for initial filtration can help extend the life of RO membranes.

Alternative and Complementary Solutions

1. Whole House Filtration System

For homes with high TDS throughout the water source, a whole house filtration system can be a more comprehensive solution. These systems typically involve a combination of sediment filters, activated carbon, and softeners installed at the point of water entry into the home. While they don't reduce TDS as effectively as RO, they can improve overall water quality for all household needs.

The essential components in a whole house system include:

• Hydropro FRP Polyglass Filter Tanks for the filter housing
• Pentair Autotrol Automatic Filter Valves for automatic control
• Wellmate Pressure Storage Tanks for maintaining stable water pressure

2. Ultrafiltration (UF) as an Alternative

For situations where extreme TDS reduction is not required, ultrafiltration (UF) systems can be a good alternative. UF is effective in removing suspended particles, bacteria, and some viruses, while retaining essential minerals in water. Products such as Asahi Ultrafiltration Membranes or DuPont Omexell Ultrafiltration Membranes can be a good choice for this application.

3. Technology Combination

In some cases, a combination of technologies might provide the best solution. For example, using a whole house filtration system to improve overall water quality, followed by a point-of-use RO system in the kitchen for drinking water. This provides flexibility and efficiency in household water management.

Specific Considerations for Specific Water Sources

1. Well Water

Well water often has specific challenges such as high iron, manganese, and bacteria content. Before using RO, it is important to address these issues first. The use of iron filters such as Clack Birm Iron Removal Media or Inversand Manganese Greensand is highly recommended. For disinfection, UV systems such as Hydropro Ultraviolet can be an effective solution.

2. PDAM Water

Tap water is usually treated, but quality can vary depending on location. If TDS is still high, a combination of activated carbon and RO filters can be a good solution. Activated carbon filters such as Calgon Coal-based Activated Carbon are effective in removing chlorine and improving the taste of the water before it enters the RO system.

3. Areas with Seawater Intrusion

In coastal areas or areas with seawater intrusion, groundwater TDS can be very high and fluctuate. In these cases, RO systems with larger capacities and membranes designed for brackish water may be required. Products like DuPont FilmTec Brackish Water Membranes or even DuPont FilmTec Seawater Membranes may be more appropriate for these conditions.

Recent Innovations in Household RO Technology

Technological developments continue to bring innovations in household RO systems. Some of the latest trends include:

• Water-saving RO systems with lower discharge ratio
• Integration of smart home technology for remote monitoring and control
• Use of nanocomposite membranes for higher efficiency
• Space-saving tankless RO system

Products like the Pentair Merlin Undersink Reverse Osmosis reflect some of these innovations, offering more efficient and environmentally friendly systems.

Conclusion

The use of Reverse Osmosis systems for household water with a TDS of 500-2000 mg/L can be a very effective solution to improve drinking water quality. However, the decision to install an RO system should consider a variety of factors including raw water quality, household specific needs, cost, and long-term maintenance.

It is important to conduct a thorough analysis of the RO system and its potential benefits.

It is important to conduct a thorough analysis of your water and consult with a water treatment expert before making a decision. Each home has unique needs, and the right solution may involve a combination of different water treatment technologies.

With the proper selection of a system and the specific needs of the household, cost, and long-term maintenance should be considered.

With proper system selection and good maintenance, you can enjoy high-quality water in your home, providing long-term health benefits for the whole family. Remember that an investment in a quality water treatment system is an investment in your health and the comfort of your life.

Questions and Answers

Q1: Do RO systems remove all beneficial minerals from water?

A1: Yes, RO systems do remove most minerals from water, including the beneficial ones. However, many modern RO systems come with a remineralization stage that adds important minerals back into the water. Alternatively, you could consider using a post-RO filter that adds minerals or consuming minerals from other food sources.

Q2: How long do RO membranes typically last?

A2: RO membrane life varies depending on raw water quality and usage, but can generally last 2-5 years. Good maintenance, including proper pretreatment and regular cleaning, can extend membrane life. It is important to periodically monitor the RO produced water quality and replace the membranes when their efficiency begins to decline.

Q3: Are RO systems effective in removing microplastics from water?

A3: Yes, RO systems are very effective in removing microplastics from water. RO membranes have very small pores (about 0.0001 microns) that are able to filter out microplastic particles that are generally between 1 micron to 5 millimeters in size. This makes RO one of the most effective methods for removing microplastics from drinking water.

References

1. Byrne, W. "Reverse osmosis a practical guide for industrial users." (2nd ed.). Tall Oaks Publishing. p. 184.

"The peak daily flow was about 11,300 gallons. Unfortunately, this flow could occur over several subsequent days. It would not be possible to undersize the RO system and rely on storage as a means to allow the RO to catch up. Also, space was limited for installing additional storage tanks."

2. Byrne, W. "Reverse osmosis a practical guide for industrial users." (2nd ed.). Tall Oaks Publishing. p. 8.

"Reverse osmosis (RO) has become a popular water treatment technology, requiring the separation of a dissolved solute from its solvent, usually water. The most common application of RO is the purification of water, involving the removal of undesirable contaminants."

3. Byrne, W. "Reverse osmosis a practical guide for industrial users." (2nd ed.). Tall Oaks Publishing. p. 171.

"Most water treatment systems are not designed to handle more than a 6- to 10-fold loss of pressure across the cartridge filters. This limitation on how small the membrane pores can be is due to the risk of the flat sheet membrane getting clogged or damaged."

4. Byrne, W. "Reverse osmosis a practical guide for industrial users." (2nd ed.). Tall Oaks Publishing. p. 179.

"RO is commonly used to recover a low-total dissolved solids (low-TDS) water from oily waste waters in various industrial applications. A rule of thumb is that the water should contain less than 60 ppm of total dissolved solids before being used for a 'spot-free' rinse."

5. Byrne, W. "Reverse osmosis a practical guide for industrial users." (2nd ed.). Tall Oaks Publishing. p. 47.

"The osmotic pressure is a function of the concentration of total dissolved solids (TDS) in the water, which can be measured or estimated using conductivity. The TDS can be used to calculate the average osmotic pressure, which is important for designing RO systems to concentrate organic solutes."