Reverse Osmosis (RO) is recognised as the most efficient and popular way of purifying water. The RO process cleans water by separating heavy metals, dissolved salts, etc, contributing to a reduced TDS(Total Dissolved Solids) levels in our drinking water, making it pure, safe, for our regular consumption. With many smart hybrid water purifiers incorporating RO systems in them, it is invaluable in all modern households.
However, the only issue using a RO-based purification system is the water generated, also called “reject water”. This reject water contains the impurities eliminated from the purified water like the salts, and minerals, and other impurities making it unfit for drinking. For those of us focused on sustainability and worried about water wastage incurred, here are the ways you can reuse the RO reject water.
Understanding RO Waste Water
The RO purification generates wastewater in a ratio to the purified water produced. For most traditional RO systems, the waste-to-purified water ratio is around 3:1, meaning that for every litre of purified water, approximately three litres of wastewater are generated. Some advanced RO systems claim a more efficient ratio of 2:1, but the waste still remains significant.
Several factors influence the wastewater ratio:
- Quality of Input Water: Higher levels Total Dissolved Solids (TDS) in the source water require more filtration, leading to more wastewater production.
- Type of RO System: Modern, high-efficiency RO units are designed to reduce water wastage by optimising filtration processes and minimising reject water.
- Water Pressure: Lower water pressure can decrease the efficiency of the filtration process, causing an increase in wastewater production.
- Temperature of Water: Warmer water generally passes through RO membranes more easily, which can help reduce wastewater generation.
Safe and Effective Uses of RO Waste Water
- Household Cleaning:
RO wastewater can be used in household chores like to mop floors, wipe surfaces, and clean windows. You can also use this water to wash bathroom fixtures like sinks and toilets.
- Laundry Pre-rinse:
Pre-rinsing your laundry with reject water is an effective way to conserve it. It also helps in reduced detergent usage in the actual rinse cycle.
Toilet Flushing:
Did you know that Japanese use the greywater cycling to treat waste water from showering, baths and sinks, etc, for their non-potable uses like flushing toilets? Similarly, RO reject water can be employed for this purpose for a sustainable way forward.
- Gardening and Irrigation:
Most plants can thrive with wastewater, especially those that are less sensitive to minerals. Test it on a few plants first, but generally, it can be beneficial for gardens and indoor plants, particularly if TDS levels are below 2000 ppm.
- Vehicle Washing:
Cleaning your vehicles with the reject water is one of the popular and easy ways of utilising it without the need for any complicated mechanisms for conservation.
- Pre-rinsing Utensils:
Use the RO waste water for pre-rinsing the utensils before the actual cleaning. YOu could also go ahead and use it for cleaning if the water is not too hard and doesn’t leave any soap scum.
Precautions When Using RO Waste Water
- Monitoring TDS Levels: Before using the reject water for the above mentioned applications, make sure to test the TDS level.
- Avoiding Use on Delicate Plants: If the TDS levels are high, avoid using it for purposes of gardening or for watering delicate plants.
- Preventing Scale Build-up: Further if the reject water is hard, it can lead to buildup on appliances or leaves white patches after usage. In such cases, dilute it with regular water.
Tips for Reducing RO Waste Water Generation
Primarily this involves checking the waste-to-purified water ratio before buying a water purifier. Lesser the ratio, lower is the waste generated.
Some purifiers come with an option to push the rejected water back to the overhead tank which then gets purified again. This way now water gets wasted.
After purchase, regular maintenance of your water purifier ensures an efficient water purification which could translate to less water wasted as a result.
By reusing RO waste water for everyday tasks, you not only save water but also contribute to a more sustainable lifestyle. From gardening to cleaning, there are plenty of creative ways to make the most of this resource. Small changes can lead to big results—let's reduce waste and make every drop count!
FAQ Section
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Can RO waste water be used for plants?
Yes, RO waste water can be used for plants, but it is important to monitor the TDS levels. Most plants tolerate water with TDS levels up to 2000 ppm, but delicate plants may not do well with it. Always test the water on a small area first. -
What are the best ways to reuse RO waste water?
RO waste water can be reused for mopping floors, washing cars, watering plants, cleaning toilets, and even in your washing machine for laundry pre-rinse. It’s a great way to conserve water for household tasks. -
How can we reduce waste water from RO systems?
To reduce RO waste water, consider using a water-saving RO system with a better waste-to-purified water ratio (e.g., 1:1). You can also collect the waste water and use it for non-potable purposes. -
Is RO waste water harmful?
RO waste water is not safe for drinking or bathing due to the high concentration of impurities. However, it can be safely reused for non-consumable purposes like cleaning or gardening after ensuring its TDS levels are suitable. -
Can RO waste water be used in washing machines?
Yes, RO waste water can be used in washing machines for tasks like pre-rinsing clothes. Just ensure that the TDS level is not too high, as this could affect the cleanliness of clothes over time.
