Water Tank Size Calculator India — Ideal Capacity for Your Household
Find the ideal water tank capacity for your household based on family members, daily usage per person, and supply gap duration.
What size water tank for a 4-member family in India?
Per IS 1172: 4 persons × 135 L/day = 540 L/day. With 20% buffer: 648 L. Recommended overhead tank: 1000 litres (Sintex/Aqualite NTB 1000). For areas with alternate-day supply (very common in Indian cities): need 2000L overhead + 3000L underground sump. For municipal supply: 1000L overhead tank is sufficient.
IS 1172 Formula: Daily Demand = Persons × 135 L | Tank Size = Daily Demand × Days × 1.2 (buffer) → Next standard size (500/1000/1500/2000/3000/5000 L)
💧 Water Tank Capacity Calculator
Calculate recommended tank size for overhead or underground storage
Standard IS 1172: 135 L/person/day
How many days to store water for
Extra capacity for wastage/leakage
Recommended Tank Capacity
Recommended Water Tank Sizes for Indian Homes — IS 1172 (2026)
Based on 135 LPCD (IS 1172 residential standard). Overhead tank for 1-day storage + 20% buffer. Sintex, Aqualite, Vectus, and Penguin standard sizes.
Family Size
Daily Need
1-Day + Buffer
Overhead Tank
Underground Sump
Brand Reference
Estimated Cost
2 members
270 L/day
324 L
500 L
750–1000 L
Sintex NTB 500L
₹8,000–18,000
4 members
540 L/day
648 L
1000 L
1500–2000 L
Sintex NTB 1000L
₹15,000–28,000
6 members
810 L/day
972 L
1000 L
2000–3000 L
Sintex NTB 1000L
₹20,000–40,000
8 members
1080 L/day
1296 L
1500 L
3000–5000 L
Sintex NTB 1500L
₹30,000–60,000
10 members
1350 L/day
1620 L
2000 L
5000 L
Sintex NTB 2000L
₹40,000–80,000
Apartment 20 flats
2700 L/day
3240 L
3000 L (per block)
10000 L
Triple-layer FRP
₹1L–3L+
IS 1172: Residential 135 LPCD | Rural 70 LPCD | Luxury/Premium 200 LPCD. Prices include standard installation.
Frequently Asked Questions — Water Tank Size Calculator
How do I calculate water tank size for my house?
Per capita daily water requirement: 135 litres/person (IS 1172). For a 4-member family with daily supply: 4 × 135 = 540 litres. For storage covering 1 day outage: 540 litres. Recommended overhead tank: 1000 litres (next standard size above 540L). For 2-day storage: 2000 litres.
What is the standard water requirement per person per day in India?
As per IS 1172: residential use = 135 litres per capita per day (LPCD). This includes drinking, cooking, bathing, washing, and flushing. For luxury residences: 150–200 LPCD. For rural areas per CPHEEO guidelines: 70 LPCD minimum. For high-rise apartments: 135–150 LPCD.
What is the recommended water tank capacity for a 4-member family?
Daily requirement: 4 × 135 = 540 litres. For 1-day storage overhead tank: 500–1000 litres (1000L recommended). For underground sump with 2-day storage: 1000–1500 litres. Total system: 500L overhead + 1000L sump = 1500L for comfortable daily use with municipal supply.
What are standard water tank sizes available in India?
Common plastic overhead tank sizes in India: 500L, 1000L, 1500L, 2000L, 3000L, 5000L, 10000L. Common brands: Sintex, Aqualite, Ashirvad, Supreme. Underground sumps are custom-built: 2000–10000L for residential. Sizes above 5000L typically require structural/civil RCC tanks.
What size water pump is needed for a 1000-litre overhead tank?
For filling a 1000L tank from 5m depth (sump): use a 0.5 HP self-priming pump. Filling time ≈ 30 minutes. For 2000L tank from 10m depth: use 1 HP pump. For borewell (100m depth): use 1–1.5 HP submersible pump. Pump size depends on flow rate required and total head (suction + delivery height).
Is underground water sump or overhead water tank better?
Use both: underground sump collects municipal supply and stores larger volumes. Overhead tank provides gravity-fed water pressure throughout the house. Sump-to-overhead system is standard for Indian homes. Underground capacity: 2× daily requirement. Overhead: 1× daily requirement. System total: 3× daily usage.
How much does a 1000-litre water tank cost in India?
Sintex 1000L overhead tank: ₹5,500–₹7,500 (2026 prices). Aqualite/Supreme 1000L: ₹4,500–₹6,000. Installation (platform/plumbing): ₹3,000–₹8,000 additional. For a complete system with platform: ₹10,000–₹20,000. RCC underground sump (2000L): ₹15,000–₹40,000 depending on construction.
What material is best for water storage tanks in India?
Triple-layer LLDPE plastic tanks: UV-resistant, anti-bacterial, food-grade — best for overhead use. Single-layer FRP (fibre): durable but brittle. RCC underground sump: permanent, large capacity. GRP tanks for rooftop: commercial use. Avoid galvanized iron for potable water — prone to rust and contamination.
How do I calculate the dimensions of a rectangular water tank?
Given volume in litres: convert to m³ (divide by 1000). Choose L:W:H ratio (2:1:1 is common). For a 2000L tank: 2 m³. Let L = 2x, W = x, H = x: 2x × x × x = 2x³ = 2 → x = 1. So dimensions: 2m × 1m × 1m. Adjust to practical construction sizes.
What is the minimum height for a water storage tank?
Minimum 2–3 metres above the highest water outlet (top floor shower) for adequate pressure. Rule of thumb: 10 metres height = 1 bar pressure. For a G+1 house (8m total height), tank should be at 10–12m height for good pressure. Booster pumps can compensate for insufficient height.
How much water is wasted through typical household leaks?
A dripping tap wastes 15–30 litres per day. A continuously running toilet: 200–400 litres/day. Pipe leaks: variable. Average Indian household loses 15–25% of water to leaks. This means tank size should be increased by 15–20% to account for wastage if leak detection/plumbing is not maintained.
What is the rule of thumb for water storage in apartments?
For multi-storey apartments: calculate per-flat daily usage (135L per person × avg family size = 4.5 persons × 135 = 610L/flat). Total building sump: number of flats × daily usage × 1.5 (safety factor). Overhead tank: 1 day supply for all flats. Terrace tanks of 1000L per 3 flats is a common thumb rule.
Can I store water in a black plastic tank?
Dark-colored tanks (black or dark blue) prevent algae growth by blocking UV light but absorb more heat, making water warm. Triple-layer tanks with a white outer and black inner layer combine UV protection with temperature control. In hot Indian climates, shade your overhead tank or use insulated triple-layer tanks.
What is the maintenance required for water storage tanks?
Clean tanks every 6 months: drain completely, scrub interior with mild chlorine solution (1:100 dilution), rinse thoroughly, refill. Check inlet/outlet valves and ball cock for wear. Inspect for cracks annually. Replace rubber seals every 2–3 years. Sanitize after any contamination event with chlorination.
How long can water be stored safely in a plastic tank?
Water stored in food-grade plastic tanks away from sunlight is safe for 3–6 months if properly sealed and not contaminated. For daily use tanks (filled regularly), freshness is maintained naturally. Do not store water in tanks exposed to direct sunlight without UV protection — breeds bacteria and algae rapidly.
What is the pressure difference between a 1000L and 2000L tank at the same height?
Water pressure depends only on height, not volume. A 1000L tank and a 2000L tank at the same height (say 5m) provide exactly the same pressure: P = ρgh = 1000 × 9.81 × 5 = 49,050 Pa ≈ 0.49 bar. Volume determines how long the pressure lasts (flow duration), not the pressure itself.
How do I calculate the pipeline diameter for water supply from an overhead tank?
For a household with 4 outlets simultaneously drawing water at 15 L/min each: total flow = 60 L/min = 1 L/sec. Using pipe velocity formula: A = Q/v where v = 1.5 m/s (recommended). A = 0.001/1.5 = 0.000667 m². Diameter = √(4A/π) = 29mm → use 32mm (1.25 inch) pipe.
What is the CPHEEO standard for water storage in Indian cities?
CPHEEO (Central Public Health and Environmental Engineering Organization) guidelines: overhead storage = 1/3 of daily demand per zone, to balance peak demand. For residential areas: overhead tanks are sized for 2–4 hours of peak demand. Underground sumps hold 1–2 days of total demand.
How many litres per day does a typical Indian family use?
Average Indian household (4.5 persons): total daily water use = 4.5 × 135 = 608 litres. Breakdown: flushing (30%), bathing (25%), washing clothes (20%), kitchen (15%), drinking/cooking (10%). Urban households with western-style bathrooms use more. Rural households: 55–70 LPCD if no flush toilets.
Water Tank Tips for Indian Homes — Size, Pressure & Maintenance
Expert guidance on water tank selection and installation for Indian residential properties.
💡 Triple-Layer Tanks are Best
Triple-layer LLDPE tanks (white outer, carbon black middle UV-shield, white food-grade inner) provide UV protection, temperature control, and anti-bacterial properties — essential for Indian climate. Brands: Sintex TUFF, Vectus Triple Layer.
💡 Height for Good Pressure
Install overhead tank at least 2m above highest tap for gravity flow. Rule: 10m height = 1 bar pressure. For 2nd floor shower (needs 0.5 bar): tank must be at 5m minimum above ground floor. Use booster pump if insufficient height.
💡 Clean Tank Every 6 Months
Biofilm and algae accumulate in tanks causing typhoid and gastroenteritis — major health risks in India. Clean with 1% chlorine (1L bleach in 100L water). BIS recommends quarterly inspection for potable water storage tanks.
💡 Pump Sizing Guide India
1000L from 5m depth: 0.5 HP fills in ~30 min. 2000L from 10m: 1 HP. Borewell at 100m depth: 1–1.5 HP submersible. Always buy pumps from ISI-marked brands: Kirloskar, CRI, Grundfos, V-Guard.
