Rainwater Harvesting in Bengaluru: Best Storage Methods + BWSSB Rules Explained

The water story in Bengaluru is a combination of contradiction and irony. The city is home to thousands of startups and IT companies. But, sadly, it is grappling with water scarcity. The BWSSB can only supply around 900 million litres per day against an estimated demand of 1.5 billion litres daily. The demand gap is being filled by over 1,700 water tankers operating across the city. The problem lies in the nexus among the tanker mafia, political networks, and BWSSB officials. Tanker operators have been known to create artificial shortages. For a middle-class family, this adds up fast in terms of cost. This is a problem that can be effectively addressed by rainwater harvesting. It's also now mandatory under BWSSB regulations, with penalties reaching up to ₹5,000 and higher water bills for non-compliance. This guide helps you understand the rules and how to use rainwater harvesting in Bengaluru to address the water crisis.

The BWSSB Rules in Bengaluru

The BWSSB has made rainwater harvesting mandatory for residents in Bengaluru. If you don't want to be penalised, it's important to understand the BWSSB rainwater harvesting rules.

Who Is Rainwater Harvesting Mandatory For?

The rule divides the residential complexes into two categories –

• Existing Buildings (built before 2009): If your property is 60 ft × 40 ft (2,400 sq. ft.) or larger, RWH is mandatory. The BWSSB gave existing homeowners until 2009 to comply, and enforcement has tightened since then.
• New Buildings (constructed after 2009): All new constructions on sites measuring 30 ft × 40 ft (1,200 sq. ft.) or larger must have an RWH system. Builders cannot get occupancy certificates without proving compliance.

The calculations

This is the legal formula BWSSB uses to determine your exact storage/recharge capacity requirement- Storage/Recharge Capacity = (Roof Area in sq. m × 20 liters) + (Paved Open Area in sq. m × 10 liters) Here is what it means –

• 20 liters per square meter of roof area – This accounts for rainwater collected from your rooftop
• 10 liters per square meter of paved open space – This covers driveways, terraces, and other non-permeable surfaces

A typical 30×40 ft house has: Roof area: ~1,200 sq. ft. = ~111 sq. m Paved area: ~500 sq. ft. = ~46 sq. m Required capacity = (111 × 20) + (46 × 10) = 2,220 + 460 = 2,680 liters You don't need to store all 2,680 liters in a tank. You can split it: store some in a sump, recharge the rest to groundwater through a recharge well.

The Penalties

BWSSB does not levy the fines separately. Instead, these fines and penalties charge them to your water bill.

• Initial Non-Compliance - You'll see an "Other Charges" section on your water bill. For the first 3 months of non-compliance, this is typically 50% of your monthly water bill amount.
• Escalated penalty – After three months, the penalty will be 100% of your monthly water bill.

Additionally, recent directives have introduced ₹5,000 penalties for water misuse and ₹500 daily fines for continued violations, showing BWSSB's serious enforcement stance.

How to prove compliance as per the BWSSB rules?

If you want to escape the penalties, you are expected to show a functioning rainwater harvesting system. Here is what you should do to ensure compliance – Installation Get your system installed by a qualified contractor (preferably BWSSB-trained plumbers) Self-Declaration Form + Photos Submit a self-declaration form along with photographs showing:

• The gutters and downpipes
• The storage tank or sump connection
• The recharge well (if applicable)
• The filter system

Submission Take these documents to your local BWSSB sub-division office.

Best Storage Methods for Bengaluru Homes

Here are a few of the best rainwater harvesting storage methods –

Method 1: Store & Reuse (Sump Connection) – Most Practical

It is the most simple method. It involves collecting rainwater from your rooftop, channelling it through pipes, filtering it, and diverting it directly into your existing underground sump tank. What makes it the best choice?

• Cheapest option – Uses your existing sump, so minimal cost
• Immediate results – You reduce BWSSB/tanker water dependency from day one
• Low maintenance – Just clean the filter periodically
• Satisfies BWSSB mandate – Proves functional usage

The Cons  The quality of rainwater is of the most importance. You are expected to use proper filtration systems. We recommend the mandatory use of the First Flush Separator.

Method 2: Groundwater Recharge (Ring Well) – Long-Term Vision

The method uses rainwater to recharge the well. You need not necessarily use it for storing or immediate usage. This replenishes groundwater levels over time. What makes it a good option?

• Refills your borewell – Gradually improves groundwater availability
• Reduces flooding – Prevents water from stagnating on surfaces
• Supports sustainability – You're giving back to the aquifer

Note – The method is mandatory for the "10 liters per sq. m" paved areas. The cons You will not have direct access to the water. It can take several months for the water to percolate through the ground. Pro Tip – The best method would be to use a combination of method 1 and method 2 for the optimum use of rainwater.

Method 3: Rain Barrels (Above-Ground Tanks) – For Specific Needs

This involves the use of HDPE (high-density polyethylene) tanks placed on your terrace, or ground collect and store rainwater. You can use tanks with a capacity of 500–2,000 liters. Why is it a preferred method?

• Easy retrofitting (no digging required)
• Perfect for gardening and car washing
• Quick to install
• Visible proof of compliance

The Cons It has limited storage capacity. The water collected is exposed to heat and sunlight. Moreover, the tanks may require frequent cleaning.

Method 4: The Hybrid System (The "Gold Standard")

Most of the consultants in Bengaluru recommend this method. In fact, it is considered to be the most intelligent approach. In this method, the rainwater is collected after filtering into a tank or storage. The overflowing water is fed to the groundwater recharge system. Why it is ideal?

• Meets BWSSB mandate perfectly – It satisfies both the 20 liters/sq. m (storage) and 10 liters/sq. m (recharge) requirements
• Maximizes water utility – You get immediate use AND groundwater recharge
• Cost-effective – Single filter handles both paths; no redundant installations
• Future-proof – As groundwater recovers, you can increase recharge capacity

Essential Components: The Technical Must-Haves

The rainwater harvesting system requires a few components that are specifically designed for your specific needs. Here are the prime components of a rainwater harvesting- Gutters & Downpipes PVC is primarily used for gutters and downpipes. The size recommendations would be –

• 90 mm diameter – For roof areas up to 150 sq. m
• 110 mm diameter – For larger areas

We recommend using UV-resistant PVC or UPVC (unplasticized PVC). The summers in Bengaluru are very brutal. They can damage the pipes. The First Flush Separator (Critical!) This is the most essential component in a rainwater harvesting system. The first rains flush out leaves and other debris from your rooftop. A First Flush Separator is a simple T-junction pipe system that diverts and discards this dirty water before it enters your sump. Note – This is the most essential component of your rainwater harvesting system. Without it, your rainwater harvesting system, worth Rs 80000, would not work as expected. Filtration Systems In Bengaluru, we typically recommend two types of filtration systems.

• Wall-mounted filters – They work best for most homes. These filters require minimal maintenance.
• Sand bed filters – they let water pass through layers of sand, charcoal, and gravel. However, these systems require high maintenance.

We at Euroguard recommend wall-mounted filters for homes in Bengaluru. They offer the following advantages –

• Low maintenance (crucial during monsoons when you're busy)
• Self-cleaning means consistent performance
• More durable in humid, high-heat conditions

Installation Costs & Maintenance: What You'll Actually Spend

The cost of rainwater harvesting in Bengaluru depends on multiple factors.

Home Type	Size	Estimated Cost	Components Included
Small Home	30×40 ft (1,200 sq. ft.)	₹20,000–₹40,000	Basic piping, filter, storage connection
Medium Home	40×50 ft (2,000 sq. ft.)	₹40,000–₹70,000	Piping, filter, sump upgrade, recharge pit
Large Home/Villa	60×80 ft+ (5,000+ sq. ft.)	₹70,000–₹1,20,000	Multiple tanks, advanced filters, recharge well
Apartment Complex	10–20 flats	₹2–5 lakhs+	Common tanks, shared filters, multiple wells

Maintenance Checklist (Easy & Affordable)

Rainwater harvesting systems require consistent maintenance. Pre-Monsoon (May)

• Clean your roof and gutters (remove dry leaves, debris)
• Check downpipe connections for leaks
• Inspect filter mesh for damage
• Estimate time: 1–2 hours

During Monsoon (June–September)

• Check the First Flush cap. Make sure that it is functioning
• Monitor sump water level
• Visual inspection for leaks in piping

Post-Monsoon (October)

• Clean filter mesh thoroughly
• Check recharge well for blockages
• Disinfect sump with chlorine if water quality seems questionable
• Estimate time: 2–3 hours

Step-by-Step Guide to Getting Started

The requirements from BWSSB may appear to be daunting. But, you need not fret. It is quite easy and simple to handle the task if you go through installation process carefully. Step 1: Calculate Your Roof Area

• Measure the length and breadth of your roof
• Multiply to get total roof area in sq. meters

Example: A 30×40 ft house = 12m × 12m = 144 sq. m roof area Step 2: Determine Your Required Capacity Use the formula mandated by BWSSB. (Roof area × 20) + (Paved area × 10) Step 3: Choose Your Storage Strategy Your storage capacity would depend on your budget. If you are budget conscious, you can go with only the sump connection. If you are looking for a full connection, you can choose a Hybrid system with a recharge well. Step 4: Hire a Qualified Contractor Seek guidance and recommendations from the neighbors who have installed the system. You can also get in touch with BWSSB. They generally have a list of qualified and empanelled installers. Step 5: Get Installation & Documentation Follow the steps here below –

• Ensure contractor installs all components (gutters, filters, First Flush, pipes)
• Take photographs during installation
• Request an installation certificate (if contractor provides one)

Submit the installation details and relevant photographs to BWSSB. BWSSB will processyour application in one or two weeks.

Conclusion

The water crisis in Bengaluru is real. Rainwater harvesting is one excellent means to take control of the situation. It should definitely be a financially viable solution. Euroguard Hysquare offer you the best uPVC gutter system that's changing the game in Bengaluru. We offer durable and aesthetic looking gutter pipes that offer both looks and functionality. Don't wait for the next drought. Plan your system today. Contact a BWSSB-trained contractor this month, and by next monsoon, you'll have a functioning system that cuts your water dependency, stops the fines, and reclaims your home's water security.