IS 7558:1974 is the Indian Standard (BIS) for domestic hot water installations. This code of practice provides guidelines for the design and installation of domestic hot water systems in buildings. It covers aspects like sizing of water heaters and storage tanks, pipework design, material selection, and necessary safety controls. The standard aims to ensure an adequate and safe supply of hot water for various domestic uses.
Code of practice for domestic hot water installations
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Minimum Hot Water Storage Temperature | 60°C recommended for general purposes (Clause 5.1.1) | ≥60°C (Mandatory for Legionella control) | BS 8558:2015 |
| Maximum Delivery Temperature at Tap (Anti-Scald) | Not specified; relies on user mixing. | 45°C (for care facilities) to 50°C (general ablution) via TMVs | AS/NZS 3500.4:2021 |
| Approved Plastic Pipe for Hot Water | None specified (focuses on Copper and Galvanized Iron). | PEX, CPVC, PE-RT, PP-R, etc. | International Plumbing Code (IPC) 2021 |
| Safety Devices for Unvented Cylinder | General mention of safety valves; primarily deals with open-vent systems. | Mandatory combination of Temperature & Pressure Relief (TPR) valve and Expansion Control Valve. | AS/NZS 3500.4:2021 |
| Maximum Water Velocity in Pipes | 1.5 m/s recommended to minimize noise and erosion (Clause 5.3.3.2). | Up to 2.5 - 3.0 m/s is generally considered acceptable. | BS 8558:2015 |
| Insulation Requirement for Pipes | Advises insulation to 'prevent undue heat loss'; refers to IS 3346 for material. | Prescriptive minimum thickness based on pipe diameter (e.g., 25mm insulation for 22mm pipe). | BS 8558:2015 (reflecting UK Building Regulations Part L) |
| System Focus | Predominantly open-vented, gravity-fed systems. | Comprehensive coverage of both unvented (mains pressure) and vented systems. | BS 8558:2015 |