iSpring PH100 Alkaline Reverse Osmosis Review: Who It Fits and Who Should Skip It

What stands out

• 100 GPD capacity for fast water production
• 1:1 pure to waste water ratio
• 6-stage filtration with alkaline remineralization
• Under-sink installation with quick-connect tubing
• US-made filters and Dupont membrane

Who it fits

Key specs explained for you

Capacity: 100 GPD

This rating means the system produces 100 gallons of pure water per day under standard test conditions. In practice, this supports higher daily usage for drinking, cooking, and ice making. You get a steadier supply than with slower 50 GPD units. This capacity suits larger households or those who frequently fill pitchers and appliances.

Filtration Stages: 6

The system uses six distinct layers to clean your water. This includes pre-filters, the main reverse osmosis membrane, and the final alkaline remineralization stage. More stages generally mean broader contaminant removal. You benefit from comprehensive filtration that targets sediment, chlorine, and dissolved solids before the water reaches your faucet.

Filtration Type: Reverse osmosis, alkaline

This combination removes impurities while adding back beneficial minerals. Standard reverse osmosis can leave water slightly acidic. The added alkaline stage restores pH balance and improves taste. You get cleaner water that is also more pleasant to drink. This type is ideal if you prefer balanced mineral content over purely filtered water.

Pure to Drain Ratio: 1:1

For every one gallon of clean water produced, one gallon is sent to the drain. This ratio is efficient for modern systems. Older units often waste three or four gallons for every gallon of clean water. You save on water bills and reduce environmental impact. This efficiency makes the system more sustainable for long-term use.

Installation Type: Under sink

This unit is designed to fit beneath your kitchen sink. It connects directly to your cold water line and uses a dedicated faucet. You save counter space and keep the system out of sight. Ensure you have enough cabinet space, as the unit measures 16 by 17.5 by 19 inches. This setup is standard for home installations.

iSpring PH100 Design and Build Specs

The iSpring PH100 measures 17.5 inches long, 16 inches wide, and 19 inches high, according to the listing. This white multi-stage filtration assembly is built for an under-sink layout and fits standard kitchen cabinets. Its first-stage filter canister features a clear, see-through housing. This transparent build allows you to visually inspect sediment buildup directly without opening the system or turning off your supply line.

For water connections, the design uses upgraded 3/8-inch input and output lines to help increase flow rates. Plumbing the unit relies on quick-fitting connectors where you push tubing half an inch deep to lock the seal, removing the need for threaded pipes. According to the listing, the package includes dedicated installation tool sets alongside clear manuals and video guides to assist assembly under your counter.

At the sink deck, the system dispenses through an included European-designed faucet with an all-metal construction and a brushed nickel finish. This dedicated tap provides a separate point of use for treated drinking water. Inside the six-stage sequence, the unit houses US-made filter cartridges and a Dupont reverse osmosis membrane, pairing durable internal filtration components with standard under-counter dimensions.

Setup and everyday use guide

The iSpring PH100 is designed for under-sink installation. You can install it yourself in a couple of hours. The system includes extra tool sets and clear manuals. Video support is also available if you need help. The unit uses quick-fitting connectors. You simply push the tubing half an inch deep into the ports. This design means you do not need to thread pipes. The first stage housing is see-through. This allows you to inspect the filter easily without removing it. The system fits under a standard kitchen sink. Its dimensions are 16 inches wide, 17.5 inches long, and 19 inches tall. You should measure your cabinet space before starting. Daily use involves connecting the system to your water line. The 100 GPD capacity provides a steady flow of water. It features a 1:1 pure-to-drain ratio. This means less waste water during operation. You can use the water for drinking, cooking, and making ice. The system includes a brushed nickel all-metal faucet. This is part of the European design. The alkaline remineralization stage adds healthy minerals back into the water. This improves the taste compared to standard RO systems. The unit is made in the US. Filters are also US-made. You can replace filters by searching for specific part numbers. The manufacturer offers lifetime support from Atlanta, Georgia. This setup is straightforward for most homeowners.

Before you buy the iSpring PH100

You should verify your cabinet space before ordering. The unit measures 16 by 17.5 by 19 inches. You need clearance for the quick-fitting connectors and tubing. The system requires a standard 3/8 inch input line. You must check your sink’s faucet hole. This model includes a brushed nickel faucet. If you already have one, you may need to remove it. You will need replacement filters for ongoing use. Search for F9KUS or F19K100US for US-made options. You should also consider a separate ice maker line if you want filtered ice. Search B09MV3SNT3 for that accessory. This alkaline system suits those who want higher pH water. It fits alongside classic RO options if you prefer remineralized taste. You need to plan for filter changes every six to twelve months. This upkeep ensures the 1:1 waste ratio stays efficient. You should compare this 6-stage setup with 5-stage versions if you do not need alkaline adjustment.

Check before you buy

• Measure your under-sink cabinet space for 16 by 17.5 by 19 inches.
• Check if you need a new faucet or can reuse your existing one.
• Confirm you have a 3/8 inch water line connection available.
• Decide if you want filtered ice and need the separate B09MV3SNT3 line.
• Plan for F9KUS or F19K100US replacement filters every six to twelve months.

The product at a glance

1

iSpring PH100 100 GPD Alkaline RO

Best for: High-flow alkaline drinking water

Filtration Stages

6

Capacity (GPD)

100

Pure to Drain Ratio

1:1

Filtration Type

Reverse osmosis, alkaline

Installation Type

Under sink

Capacity

100 GPD

View on Amazon: iSpring PH100 100 GPD Alkaline RO Affiliate link

The iSpring PH100 is a 6-stage under-sink reverse osmosis system with a 100 GPD capacity. It uses a DuPont membrane to remove up to 99% of contaminants, including lead and PFAS. The added alkaline stage remineralizes water for better taste. It maintains a 1:1 pure-to-waste water ratio. The unit measures 17.5 by 16 by 19 inches and includes a brushed nickel faucet.

Pros

• 100 GPD capacity for fast flow
• 6-stage filtration with alkaline remineralization
• 1:1 pure to waste water ratio
• Removes up to 99% of contaminants
• Includes installation tools and clear manual

Cons

• Larger footprint at 17.5 by 16 by 19 inches
• No smart monitoring or app connectivity
• Requires under-sink space for 6 stages

Good fit if

• You want alkaline water with improved taste
• You need a high-capacity 100 GPD system
• You prefer a 1:1 waste water ratio

Skip if

• You have limited under-sink storage space
• You want a compact 5-stage system
• You prefer a system with smart features

Verdict: iSpring PH100 Alkaline RO System fits homes needing high output and better-tasting water. It suits buyers who value a 1:1 waste ratio and alkaline remineralization over a smaller footprint.

Specifications side by side

Frequently asked questions

See also

• ispring ph100 alkaline reverse osmosis alternatives
• best iSpring 5-Stage reverse osmosis systems
• best iSpring reverse osmosis systems with alkaline
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