Description
The Hydro Guard HDG-45 is a compact 4-stage reverse osmosis system designed to provide high-quality filtered drinking water from a dedicated tap at your kitchen bench.
Combining sediment filtration, activated carbon, and reverse osmosis technology, the HDG-45 reduces dissolved salts and a wide range of contaminants that standard carbon filtration alone cannot remove.
The system includes a 50 GPD reverse osmosis membrane, pressurised storage tank, dedicated drinking water tap, and Hydro Guard Quick & Easy™ replacement cartridges, making it an excellent choice for everyday drinking and cooking water.
For customers who prefer remineralised RO water, the system can also be upgraded with an additional alkaline remineralisation cartridge, creating a 5-stage RO + Alkaline system.
Ideal for: Drinking water, cooking, tea and coffee, fridge water connections, and ice makers.
Why Choose the Hydro Guard HDG-45?
- 4-stage reverse osmosis filtration
- 50 GPD RO membrane, approximately 190 litres per day nominal production
- 4.5 US gallon pressurised storage tank
- Quick & Easy sanitary replacement cartridges
- Dedicated lead-free drinking water tap
- FLOWLOK leak protection
- SHOK BLOK pressure protection
- Compact underbench design
- Straightforward ongoing servicing
- Optional 5th-stage alkaline remineralisation filter
- 3-year limited manufacturer warranty
4-Stage Reverse Osmosis Filtration
| Stage | Cartridge | Function |
| Sediment | HDG-SED5 (5 micron) | Removes dirt, rust, and fine suspended particles, protecting the downstream carbon cartridge and RO membrane |
| Carbon Block | HDG-CB5 (5 micron) | Reduces chlorine, unpleasant taste, and odour before the RO membrane, also protecting it from premature damage |
| RO Membrane | HDG-TW50 (50 GPD) | The main purification stage; forces water through a semi-permeable membrane to reduce dissolved salts and contaminants |
| Carbon Polishing | HDG-CB5P | Final treatment stage on the standard system, polishing taste before the drinking water tap |
The RO membrane is rated at 50 US gallons per day, approximately 190 litres per day. Actual production will vary depending on incoming water pressure, water temperature, and feed water quality.
Reverse osmosis can help reduce contaminants including dissolved salts, sodium, nitrates, lead, arsenic, cysts including Giardia and Cryptosporidium, and other dissolved contaminants.
Optional 5th-Stage Alkaline Upgrade
For customers who prefer remineralised RO water, the HDG-45 can be supplied with an additional alkaline remineralisation cartridge. The alkaline filter is installed after the standard four filtration stages and does not replace the carbon polishing cartridge.
| System | Filtration Sequence |
| Standard HDG-45 (4 stages) | Sediment → Carbon Block → RO Membrane → Carbon Polishing |
| HDG-45 + Alkaline (5 stages) | Sediment → Carbon Block → RO Membrane → Carbon Polishing → Alkaline Remineralisation |
Reverse osmosis removes a very high proportion of dissolved minerals from the incoming water. The additional alkaline cartridge allows the purified water to pass through mineral media before reaching the drinking water tap.
Benefits of the Alkaline Upgrade:
- Adds selected minerals back into RO water
- Can increase the pH of the final drinking water
- Provides a more mineralised taste
- Retains the standard carbon polishing stage
- Installed as an additional final treatment stage
- Easy to replace during routine servicing
Choose Your System
| System | Includes |
| Standard HDG-45 - 4 Stage | 5 micron sediment filter, 5 micron carbon block, 50 GPD RO membrane, carbon polishing filter, pressurised storage tank, dedicated drinking water tap |
| HDG-45 + Alkaline - 5 Stage | Everything in the standard HDG-45, plus an additional alkaline remineralisation cartridge |
The 5-stage option is ideal for customers who want the contaminant reduction benefits of reverse osmosis while adding selected minerals back into the final drinking water.
Quick & Easy Filter Changes
The HDG-45 uses Hydro Guard's Quick & Easy cartridge system. Unlike traditional filter housings, the complete cartridge is removed and replaced during servicing.
Benefits include:
- Quick filter changes
- Cleaner and more hygienic servicing
- No filter housing spanner required
- Less chance of water spills under the bench
- No need to handle the internal filter media
Built-In Leak Protection
FLOWLOK Leak Shut-Off
The HDG-45 includes Hydro Guard's FLOWLOK™ leak detection system, providing an additional level of protection should water be detected around the filtration unit.
SHOK BLOK Protection Valve
The SHOK BLOK™ valve helps protect the filtration system from pressure shock within the incoming water supply.
These features provide additional peace of mind for permanent underbench installations.
Pressurised Storage Tank
Reverse osmosis systems produce purified water gradually, so the HDG-45 includes a 4.5 US gallon pressurised storage tank. Filtered water is stored ready for use, providing a practical flow rate from the drinking water tap whenever required.
Dedicated Drinking Water Tap
The HDG-45 is supplied with a separate lead-free drinking water tap for installation through the kitchen bench or sink. This keeps your filtered drinking water separate from your normal kitchen mixer.
Compact Underbench Design
The HDG-45 is designed to fit neatly into most kitchen cupboards. Its narrow design helps minimise the amount of cupboard space taken up by the filtration unit.
| Dimension | Measurement |
| Height | 381 mm |
| Length | 371 mm |
| Width | 117 mm |
Replacement Filters
Replacement filters are available individually, making ongoing servicing of your Hydro Guard HDG-45 straightforward.
| Filter | Stage | Function |
| HDG-SED5 | 5 Micron Sediment Filter | Removes dirt, rust, and fine sediment from incoming water |
| HDG-CB5 | 5 Micron Carbon Block | Reduces chlorine, taste, and odour while helping protect the RO membrane |
| HDG-TW50 | 50 GPD RO Membrane | Main reverse osmosis stage, reduces dissolved salts and other contaminants |
| HDG-CB5P | Carbon Polishing Filter | Final taste and odour polishing before the drinking water tap |
| Alkaline Cartridge | Optional 5th Stage | For systems fitted with the alkaline upgrade |
For easier routine servicing, replacement cartridges can also be supplied as a Hydro Guard HDG-45 service kit. The RO membrane generally has a longer service life than the sediment and carbon cartridges, so it can be replaced separately when required. Actual replacement intervals depend on incoming water quality and water usage.
Suitable Applications
The Hydro Guard HDG-45 is ideal for:
- NZ homes
- Town and mains water supplies
- Drinking and cooking water
- Tea and coffee
- Fridge water connections
- Ice makers
- Homes with elevated dissolved mineral levels
- Customers wanting greater contaminant reduction than standard carbon filtration
- Customers wanting the option of remineralised RO water
Product Specifications
| Specification | Detail |
| Brand | Hydro Guard |
| Model | HDG-45 |
| System type | Underbench reverse osmosis |
| Standard filtration stages | 4 |
| With alkaline upgrade | 5 stages |
| RO membrane | 50 GPD |
| Nominal membrane production | Approx. 190 L/day |
| Storage tank | 4.5 US gallon |
| Sediment filtration | 5 micron |
| Carbon prefilter | 5 micron carbon block |
| Final standard filtration | Carbon polishing cartridge |
| Optional final stage | Alkaline remineralisation cartridge |
| Installation | Underbench |
| Outlet | Dedicated drinking water tap |
| Cartridge system | Hydro Guard Quick & Easy |
| Leak protection | FLOWLOK |
| Pressure protection | SHOK BLOK |
| Warranty | 3-year limited manufacturer warranty |
| Dimensions | 381 mm H × 371 mm L × 117 mm W |
Important Installation Information
The quoted 190 litres per day is the nominal production rating of the RO membrane. Actual water production will vary depending on incoming water pressure, water temperature, incoming TDS, and overall feed water quality.
For bore, tank, or rainwater supplies, we recommend having the water tested before selecting a drinking water treatment system. Additional filtration or UV disinfection may be required depending on the water source.
FAQs
How much filtered water can the HDG-45 actually produce per day?
The membrane is rated at 190 litres per day nominally, but actual production depends on incoming water pressure, temperature, and feed water quality. The 4.5 US gallon storage tank buffers this, so you're not limited to real-time membrane output when using the tap.
Do I need to test my water before installing this system?
For bore, tank, or rainwater supplies, testing is recommended before selecting a system. Depending on the results, additional filtration or UV disinfection may be needed alongside the RO system.
What's the difference between the standard system and the alkaline upgrade?
The alkaline upgrade adds a 5th filtration stage after the standard carbon polishing cartridge, remineralising the water and raising its pH for a less "flat" taste. It doesn't replace any of the standard four stages, it's purely additional.
How often do the filter cartridges need replacing?
Replacement intervals depend on incoming water quality and usage. The RO membrane (HDG-TW50) generally lasts longer than the sediment and carbon cartridges, so it's often replaced on a separate schedule.
Is installation something I can do myself, or does it need a plumber?
The system is designed for underbench installation with a dedicated tap through the kitchen bench or sink. Many people install it themselves, though if you're not comfortable working with water supply lines, a plumber can complete the installation.
Does reverse osmosis remove too many minerals from the water?
RO does remove a high proportion of dissolved minerals along with contaminants, which some people prefer to counter. That's exactly what the optional alkaline upgrade addresses, adding selected minerals back in as a final stage.
Shipping
Ships nationwide across New Zealand at a fixed freight cost. Orders placed before 11 am ship the same day, subject to stock availability.