Author: Vikas Brahmavar, CEO and Co-Founder, Boson Whitewater
From preparing concrete to mixing cement and curing, water plays a crucial role in almost every stage of construction. With large-scale projects consuming thousands of litres daily, the sheer volume of water used in the construction sector is staggering. In a country where water scarcity is a growing concern, we need to find ways to reduce dependence on freshwater needs.
Recognizing this challenge, Bengaluru faced a turning point during the summer of 2024, when a severe water crisis forced the Bengaluru Water Supply and Sewerage Board (BWSSB) to take action. To ease the pressure on the city’s freshwater supply, the board introduced treated wastewater for construction, ensuring that the sector could reduce its dependence on freshwater.
With water scarcity set to worsen in the coming years, sustainable water management must become a priority. India continues to rely heavily on monsoon-dependent water planning, often overlooking the vast amounts of wastewater that flow out of cities. Wastewater, when treated and repurposed, could help bridge the gap. By integrating recycled water into construction processes, cities can take a crucial step toward long-term water security.
Construction sector’s water woes
The construction industry is facing significant challenges as it grapples with water scarcity, rising costs, and policy roadblocks.
- Expensive water procurement: With groundwater depletion, builders rely on tankers that charge unpredictable rates per load. The cost of transporting water from remote locations further inflates expenses.
- Unstable supply and quality: Water quality varies widely, and unreliable supply chains make project planning difficult.
- Policy uncertainty: Cities like Bengaluru have considered regional construction bans due to concerns over unchecked urbanization and water mismanagement.
- Market impact: Any halt in construction could reduce new property supply, drive up real estate prices, and result in job losses for construction workers.
Water quality in construction
In construction, the quality of water is very critical but it is often overlooked. Aspects such as strength and durability of cement concrete and mortar depend heavily on the chemical composition of the water used. For optimal results, construction water must be free from contaminants, maintain a balanced chloride-to-sulfate mass ratio (CSMR), and have a neutral pH. However, that’s mostly not the case with freshwater that the sector depends on.
Economic viability of using treated water
The cost of borewell water, when considering only pumping power, is around 2-2.5 paise per litre. However, recent reports from cities like Bangalore highlight a growing challenge—out of every 10 borewells, only two yield water, and even those typically provide full volume for just three years within a 10-year cycle. Factoring in drilling, maintenance, and depletion, the true cost of borewell water rises to 7-9 paise per litre, plus additional treatment costs in most cases.
In contrast, Recovered Whitewater—treated excess STP (Sewage Treatment Plant) water from apartment complexes—offers a high-quality, low-TDS alternative. This water is supplied directly to construction sites on demand, making it both cost-effective and sustainable. The cost of recovered water averages 8-10 paise per litre, plus transportation.
In the long run, adopting a MicroGrid system for Recovered Whitewater—where treated wastewater is efficiently distributed within local zones—could significantly enhance cost savings and sustainability for the real estate industry, reducing dependency on unreliable borewells and groundwater depletion
Why use recycled water?
With water shortages posing a growing challenge for the real estate sector, highly treated recycled water is emerging as a viable solution. Recycled water is purified through advanced filtration processes, removing impurities and making it suitable for construction.
With many of our cities facing a growing water crisis, the construction industry is under increasing pressure to find sustainable alternatives to freshwater. Highly treated wastewater can be purified to remove impurities and made suitable for construction use. A city like Bengaluru generates 1,400 million litres of wastewater every day, yet only 520 million liters undergo treatment. Most apartment complexes use just 20% of STP treated water for their garden and Flushing application, while the rest is discharged into drains. If this water were processed further and utilized efficiently, it could significantly reduce reliance on freshwater sources.
Recognizing this, the Karnataka State Pollution Control Board (KSPCB) is working towards making the use of recycled wastewater mandatory for construction. If there are advanced water treatment technologies, wastewater can undergo multi-stage filtration beyond the standard STP process. It can be purified to remove bacteria, heavy metals, pesticides, and salts, ensuring it meets IS 456:2000 construction standards.
