Reverse Osmosis Technology for Drinking Water: A Comprehensive Guide

What is Pure Drinking Water?

Pure drinking water is free from harmful contaminants such as bacteria, viruses, heavy metals, and dissolved salts. According to WHO (World Health Organization) and Bangladeshi BSTI (Bangladesh Standards and Testing Institution) standards, drinking water should have a TDS (Total Dissolved Solids) level below 500 mg/L, be free from pathogens, and not contain hazardous chemicals like arsenic, lead, or fluoride beyond the permissible limits.

What is Reverse Osmosis (RO)?

Reverse Osmosis (RO) is a water purification process that removes dissolved salts, contaminants, bacteria, and other impurities using a semipermeable membrane. The RO process works by applying pressure to force water molecules through the membrane while blocking larger contaminants.

RO Filtration Stages:

1.Pre-Filtration (Sediment & Carbon Filters) – Removes large particles, chlorine, and bad odors.

2.Reverse Osmosis Membrane – Eliminates dissolved solids, heavy metals, bacteria, and viruses.

3.Post Carbon Filter – Enhances taste and removes residual chemicals.

4.Mineralization (Optional) – Adds essential minerals like calcium and magnesium.

Does Bangladesh’s Raw Water (TDS <700 mg/L) Need RO?

In most regions of Bangladesh, except coastal and river-side areas, raw water has a TDS level below 700 mg/L. In these cases, RO is not always necessary. Instead, simpler filtration methods like UV, UF, Activated Carbon, and Microfiltration can effectively remove bacteria and harmful substances while retaining essential minerals.

However, RO is required in the following cases:

· High TDS (>700 mg/L): Common in coastal areas with saline water.

· Heavy Metal Contamination: If water contains arsenic, lead, or mercury beyond safe limits.

· Industrial and Urban Pollution: Areas where groundwater is contaminated with industrial waste or pesticides.

· High Nitrate or Fluoride Levels: Found in some regions of Bangladesh.

Which Water is Perfect for RO Treatment?

RO is best suited for water sources with high contamination and excessive TDS levels, including:

· Coastal areas with saline water.

· Urban areas with industrial pollutants.

· Water with heavy metal contamination (arsenic, lead, fluoride).

· Households using deep tube wells with unknown TDS levels.

Which Water Does NOT Need RO Treatment?

RO is unnecessary for:

· Municipal Water Supply: Already treated and usually has a TDS below 500 mg/L.

· Natural Groundwater (Low TDS): Water from deep wells in non-contaminated areas.

· Rural Hand-Pumped Tube Well Water: If tested safe from arsenic and pathogens.

Demerits of RO Technology

1. Removes Essential Minerals: RO eliminates healthy minerals like calcium and magnesium, which are vital for human health.

2. Wastes Water: Produces 3-5 liters of wastewater for every 1 liter of purified water.

3. High Maintenance: Requires frequent filter and membrane replacement.

4. Costly: Initial installation and maintenance costs are high.

Merits of RO, UV, and UF Filtration Technologies

Technology	Merits
RO (Reverse Osmosis)	Removes dissolved salts, heavy metals, and bacteria. Ideal for high-TDS water.
UV (Ultraviolet Filtration)	Kills bacteria and viruses. Best for municipal or rural water with low TDS.
UF (Ultrafiltration)	Filters out bacteria and sediment without removing minerals. Best for groundwater.

Does Long-Term RO Water Drinking Affect Human Health?

Yes, prolonged consumption of RO water without remineralization can cause:

· Mineral Deficiency: Lack of calcium and magnesium may lead to bone and heart issues.

· Electrolyte Imbalance: RO water lacks natural electrolytes, which are essential for hydration.

· Effects on Children: Growing children need minerals for bone and brain development, making remineralization important.

Solution:

· Use a RO system with a remineralization filter.

· Consume a balanced diet rich in essential minerals.

Which Water Filtration Technology is Best for Bangladesh?

Water Source	Recommended Filtration System
Municipal Water Supply	UV + Activated Carbon (No RO needed)
Groundwater (Low TDS)	UF + Activated Carbon (No RO needed)
Coastal/River Side Areas	RO + UV (Due to high TDS & salt content)
Industrial or Polluted Areas	RO + Activated Carbon
Rural Areas	Sand + UF + Carbon Filter (Affordable and effective)

Bangladeshi Drinking Water Standard Parameters

Parameter	BSTI Standard	WHO Standard
pH	6.5 - 8.5	6.5 - 8.5
TDS	< 500 mg/L	< 500 mg/L
Arsenic	< 0.05 mg/L	< 0.01 mg/L
Iron	< 0.3 mg/L	< 0.3 mg/L
Hardness	< 200 mg/L	< 500 mg/L
Nitrate	< 10 mg/L	< 50 mg/L

Do Bangladeshi Bottled Water and Filtered Water Maintain These Standards?

Most bottled water brands in Bangladesh claim to meet BSTI standards but may not always comply. Some issues found include:

· Higher TDS and Arsenic Levels in unregulated brands.

· Lack of proper filtration processes in small-scale brands.

For home filtration systems, certified RO, UV, and UF filters help maintain safe drinking water standards. Aquafit Technologies provides certified RO, UF, and UV filtration solutions that comply with international and national standards.

Best Simple Filtration Technology for Bangladeshi Rural and Urban Areas

· Rural Areas: Sand + UF + Activated Carbon Filter (Affordable, No Electricity Needed)

· Urban Areas: UF + UV or RO (if TDS is high)

Conclusion

Reverse Osmosis (RO) is not necessary for all water sources in Bangladesh. Most municipal and rural tube well water can be safely consumed after simple filtration methods like UV, UF, and carbon filtration. However, for high TDS or polluted areas, RO is essential. The best drinking water solution depends on TDS, contamination level, and affordability.

For reliable water filtration solutions, choose Aquafit Technologies, offering high-quality RO, UV, and UF systems tailored for Bangladesh.

Here’s a summary of trusted sources for information on drinking water and Reverse Osmosis (RO) technology:

EPA (Environmental Protection Agency) – Provides regulations and standards for safe drinking water.
WHO (World Health Organization) – Offers global guidelines on water quality and purification methods.
Desalination.com – Explains RO technology and its applications in water treatment.
Water Research Foundation (WRF) – Research-based insights on water purification processes.
CDC (Centers for Disease Control and Prevention) – Focuses on water safety and disease prevention through purification.
International Water Association (IWA) – Covers research and advancements in water treatment technologies.
These sources offer reliable, science-backed data on RO and drinking water purification