The 3kW heating element is standard for instant geysers in India, but you should check the type and material of the heating element. Incoloy or copper heating elements are known for their durability and efficiency. Otherwise glass coated heating elements are the best. Only AO Smith provide glass coated heating element in Instant geysers in India.

Instant geyser must have safety features like a thermostat to prevent overheating and a pressure relief valve to release excess pressure. As the 3kw is considered high power which put a lot of load on wiring of the house specially old houses with decade old wiring. An ELCB inbuilt instant geyser are also need of the hour to avoid electric shock. Better to connect elcb plug/top separately to geyser.

AO Smith EWS-3 Plus-White Glass Lined 3 Litre 3KW Instant Water Heater (Geyser) w/ABS outer Body |Suitable-High-rise Buildings|8 Bar High Pressure rating |Made for Kitchen and Bathroom Applications
  • Premium and stylish aesthetics: EWS Plus is an outstanding design with premium aesthetics, redefining the instant water heater category. It is a perfect balance of form and function that will make your bathroom look magnificent and extraordinary.
  • Longer Life in HARD Water Condition: AO Smith’s patented Blue Diamond glass lining in its tank provides the best protection against corrosion, even in hard water conditions.
  • HIGH-POWERED INSTANT HEATING: Get instant hot water with a high-powered incoloy heating element. Glass coating on the element further enhances the life of the heating element.
  • Stronger construction quality with tank thickness of 2 mm, 2X compared to an ordinary instant water heater
  • 5-level safety shield for maximum protection: ISI marked Power cord added safety, Auto Switch on/off- No overheating., Pressure relief valve Protection against high-pressure buildup in the tank, Superior Quality Wiring U/L Rated wiring harness for added safety, Surface Mount sensing, Thermostat is mounted on the tank. Highly consistent and reliable. Adds to the safety, Rust Proof/ Shock Proof HIPS polymer outer body
Havells Instanio 3-Litre 3KW Instant Water Heater (Geyser) White Mustard, Wall Mounting
  • Type: Instant ; Capacity: 3 Litres; Wattage: 3000 Watts; Pressure: 6.5 Bars4 Level Safety : Thermostat, Automatic Thermal Cut-Out, Pressure Release Valve and Heating Indicator
  • LED : Temperature Sensing Color changing LED Indicator for real-time hotness of the water
  • Outer Body: Rust and shock proof Plastic outer body for long life
  • Heating Element : Copper heating element offers superior heating performance with its excellent resistance to both oxidation and carbonization at high temperature setting and resists corrosion against extreme and hard water conditions
  • Inner Tank : Extra thick Stainless Steel Inner tank of superior 304 Level grade​
Bajaj Splendora 3 Litre 3KW IWH Instant Water Heater (Geyser), White
  • ABS outer body with SS tank
  • Copper heating element with efficient longer life
  • Suitable for 6 bar pressure
  • Unique Weldfree joint in outer metal body
  • It come with fire retardent cable and neon indicator for heating
Racold Pronto Pro 3L 3KW Vertical Instant Water Heater (Geyser) | Faster Heating | Suitable for High Rise Buildings | Italian Design|3 Levels of Safety|Convenient for Kitchen & Bathroom Applications
  • PUF INSULATION: the dense and thick insulation in the tank effectively retains heat, improving energy efficiency and lowering electricity costs
  • FASTER HEATING: the high-capacity heating element ensures rapid access to hot water
  • AUTO CUT OFF: the stem-type thermostat and cutout feature provide automatic temperature control and added safety for your water heater
  • NO BACK FLOW: the anti-syphoning system prevents water from flowing back into the container, thus avoiding dry heating
  • HIGH PRESSURE RESISTANCE: the water heater has high pressure withstanding capacity, which makes it suitable for high-rise buildings and high pressure pump applications
Crompton Solarium Neo 3-Litre, 3KW Instant Water Heater/Geyser with Rust Free ABS Body (Ivory)
  • PRODUCT: Crompton’s energy efficient instant water heater with rust proof ABS body
  • TECHNICAL SPECIFICATIONS: Wattage: 3000 W; Capacity: 3L; Pressure 6.5 bar
  • 4 LEVEL SAFETY: Capillary Thermostat, automatic thermal cut-out, pressure release valve and fusible plug
  • ANTI-SIPHON PROTECTION: Designed to prevent any backflow of water and protect the heating element from dry heating damage
  • QUALITY COMPONENTS: ISI marked nickel coated special element to provide resistance against scale formation
Racold Altroi+ 3L 3KW Vertical Instant Water Heater (Geyser) White, with Free Standard Installation & Pipes | Smart LED Ring | Free Electric Plug | Convenient for Kitchen & bathroom Applications
  • High Pressure Resistance: Your water heater has high pressure withstanding capacity, which makes it suitable for high-rise buildings and high pressure pump applications
  • Temperature Regulation Knob: An easy control knob through which you can regulate heating of water as per your requirement
  • Safety Plus: Three levels of safety against high temperature and pressure, provided by a hightech adjustable thermostat, cut-out and multi function safety valve according to international standards
  • Customized Application : It’s a unique, novel and first of its kind feature in the Instant water heater segment helps you in optimizing water heater usage . You can select ‘KITCHEN’ or ‘BATHING’ mode based on the intended hot water application
  • Smart LED Ring : The Smart LED Ring range senses when hot water is ready for bath, or other application and notifies user by changing LED color from blue to red
Racold Pronto Neo 1L 3Kw Vertical Instant Water Heater(Geyser), White | Faster Heating | Italian Design |Suitable for High Rise Buildings |3 Levels of Safety | Rust Proof Body | Fire Retardant Cable
  • PUF Insulation: The high density and thick PUF in your water heater ensures retention of internal heat and temperature and resulting in better energy efficiency and reduced electricity bills
  • Faster Heating: The high power heating element ensures you get hot water in no time
  • High Pressure Resistance: High pressure withstanding capacity makes it suitable for high rise buildings and high pressure pump applications
  • Safety Plus: Pronto neo provides three levels of safety against high temperature and pressure, provided by a high tech adjustable thermostat, cutout and multifunction safety valve conforming to international standards
  • Auto Cut off: Stem-type thermostat and cutout ensures automatic temperature control and extra safety for your water heater
Havells Instanio 1-Litre 3KW Instant Water Heater (Geyser), White Blue, Wall Mounting
  • Type: Instant ; Capacity: 1 Litre; Wattage: 3000 Watts; Pressure: 6.5 Bars ;4 Level Safety : Thermostat, Automatic Thermal Cut-Out, Pressure Release Valve and Heating Indicator
  • LED : Temperature Sensing Color changing LED Indicator for real-time hotness of the water
  • Outer Body: Rust and shock proof Plastic outer body for long life
  • Heating Element : Copper heating element offers superior heating performance with its excellent resistance to both oxidation and carbonization at high temperature setting and resists corrosion against extreme and hard water conditions
  • Inner Tank : Extra thick Stainless Steel Inner tank of superior 304 Level grade​
AO Smith EWS-5 White | 5 Litre 3KW Instant Water Heater (Geyser) with shock proof Outer Body |5 Levels safety shield |Made for Kitchen and Bathroom Applications
  • Instant Geyser with Express Heating: Get instant hot water with a 3000-watt high-powered heating element.
  • Longer Life: Superior quality stainless steel tank provides the best protection against corrosion in hard water conditions.
  • 5-level safety shield for maximum protection: Auto Switch on/off- No overheating, Superior Quality Wiring U/L Rated wiring harness for added safety, Pressure relief valve Protection against high-pressure build up in the tank, ISI marked Power cord added safety, Rust Proof/ Shock Proof HIPS polymer outer body
  • Instant Geyser Suitable for high-rise buildings 6.5 Bar high-pressure rating with superior quality stainless steel inner tank.
  • Complete Peace of Mind with a 5-year warranty on the tank, a 2-year warranty on the heating element, and a 2-year warranty on the overall product, the water heater/ geyser comes protected against manufacturing defects. Dial our toll-free number to arrange hassle-free assistance at your doorstep. PAN INDIA SERVICE NETWORK: AO Smith Instant Water Geysers have a Pan India Service Network.
NEXOMS Cup Type Heating Element ISI Marked 3KW Compatible for 3 Litre – 6 Litres Instant Geysers
  • Tube Material: Anti-Corrosive Copper
  • Power: 3KW
  • Heavy Quality ISI Marked Element
  • Compatible for Portable Geysers and Instant Geysers 3 Litre to 6 Litres

Another thing to check is pressure bar capacity of inner tank specially if you like high rise buildings as water pressure can be much more for tank to withhold. You can also consider 4.5kw instant geysers if the house is fairly new with new wiring.