Viomi V6 PRO vs Waterdrop G5P500A: Small-Cabinet Fit and Filter Upkeep

Cabinet space under a small kitchen sink is mostly taken by the drain trap, the shutoff valves and sometimes a garbage disposer, which leaves a narrow strip of floor for a water purifier. The Viomi V6 PRO suits that space well: a tankless reverse osmosis (RO) system with a body 5 inches wide and a faucet that shows TDS and filter life at a glance.

Households that want mineral-added water from the RO faucet will find it built into the Waterdrop G5P500A, whose composite pre-filter carries an alkaline mineralization layer. It pairs that with a mechanical faucet and filter-life lights on the main unit.

The Two Versions on the Shortlist

Both units are tankless RO systems built around two cartridges. The Viomi V6 PRO version here is model VM-V6 Pro, which arrives with its PCB composite filter and RO filter already installed, the two cartridges of its 9-stage system. A tee fitting for a refrigerator or ice maker connection comes in the box with the smart faucet.

The Waterdrop side is the standard WD-G5P500A. Its first cartridge, the G5P500A-CF, combines pre-sediment and post-carbon block stages with the mineralization layer, and the second is the G5P500-RO membrane. A bundle sold as WD-G5P500A-SET adds a spare CF filter to the same system. On both systems the first cartridge is a composite filter, and the two are rated as 9-stage and 8-stage systems.

Fit, Faucet and Filters Side by Side

Output figures, ratios and filter lifespans in the table are each brand's published values for the version compared; Waterdrop's manual gives its 500 GPD at 30 psi dynamic feed pressure and 77°F.

Converted from the two ratings, 600 GPD works out to about 0.42 gallons per minute and 500 GPD to about 0.35. On the ratio side, a rated 3:1 split means about one quarter of the water entering the system goes to the drain, and 2:1 about one third. Put another way, for every gallon of purified water, a 3:1 rating sends about a third of a gallon to the drain and a 2:1 rating about half a gallon.

Room Around the Unit: Footprint, Clearance and Setup

Neither unit needs floor space for a storage tank, which is why tankless RO systems are the usual pick for small cabinets. The Viomi V6 PRO body measures 16.3 inches long, 5 inches wide and 12.8 inches high. In a crowded cabinet, where the trap, the shutoff valves and any disposer take up the middle of the floor, the free space usually runs along the side walls, and a 5-inch-wide body is the kind of shape that planning starts from.

For the G5P500A, the planning figure Waterdrop gives in its manual is clearance: 2 inches of space around the system so it does not sit against the cabinet walls. That margin goes on every side, so the floor area to plan for is the unit plus 4 inches in each direction, 2 on each side. That margin belongs in any layout sketch alongside the trap and the valves, since it is part of the space the G5P500A occupies in practice.

The plumbing side is standard for both systems: each connects to the cold-water supply line under the sink and sends its drain line to the sink drain. For the Viomi V6 PRO, the installation parts come in the box, including the smart faucet and a tee fitting, and a step-by-step installation video follows the setup from the cold-water connection to the first flush.

Our guide to laying out an under-sink filter and its faucet covers where the faucet usually goes on the sink deck, and our walkthrough on measuring a small apartment kitchen for an RO system shows how to record the clear floor beside the trap, which helps when deciding where the unit will stand.

Where Each System Shows Filter Life

On the Viomi V6 PRO, the faucet itself is the display. It shows the real-time TDS of the purified water and the remaining life of the filters at a glance, so whoever is filling a glass sees the same information, including family members who never open the app. TDS is a reading of the total dissolved solids in the purified water, and having it beside the filter-life figure lets the household watch both numbers as the system ages. When a filter is close to its end, orange lights on the control panel come on 10 to 15 days ahead, which leaves time to order a cartridge. The Viomi app adds a third view for anyone in the household who uses it: it tracks filter life, sends a replacement reminder, compares TDS before and after filtration and keeps a usage report that shows how much purified water the household draws over time. Filter life thus shows up in three forms: as a figure on the faucet, as the orange alert on the panel and as a tracked countdown in the app.

On the G5P500A, filter status shows on the main unit under the sink. Its front panel has a CF light and an RO light that shift through blue, yellow and red as each filter nears its replacement date, and the unit beeps as a reminder. Waterdrop pairs this system with a mechanical faucet, for households that want the tap itself to stay simple.

Filter Changes Across Two Years

Both brands publish filter life in months. Laid over the first two years, starting from the filters installed on day one and counting the changes due at month 24, the published lifespans produce two different schedules.

At its rated lifespans, the Viomi V6 PRO calls for a new PCB filter at month 12 and for both the PCB and RO filters at month 24, three replacement cartridges across two change dates. The G5P500A's CF filter is rated for up to 6 months and its RO filter for up to 24 months, so the same plan puts CF changes at months 6, 12, 18 and 24 with the RO change at month 24, five replacement cartridges across four change dates. Both RO membranes share the same 24-month rating, so the whole difference over those two years comes from the pre-filter: one rated for 12 months against one rated for up to 6. For G5P500A owners, the WD-G5P500A-SET bundle puts a second CF filter on hand for that first 6-month change.

Viomi V6 PRO cartridges use a tool-free twist-lock design, and because both are rated in whole years, the changes stay on the same two dates in each two-year cycle.

For a wider look at how replacement routines compare across RO systems, see our roundup of RO filter replacement convenience by brand.

Why Some Kitchens Choose the G5P500A

Mineral-added water is the clearest reason to pick the G5P500A. Waterdrop builds an alkaline mineralization layer into the G5P500A-CF filter, which adds calcium, magnesium, sodium and potassium ions after filtration and brings the water to a pH of about 7.5, slightly above neutral, according to the filter's product page. Because the layer sits inside the existing CF cartridge, the system still runs on two filters, and the mineral stage is renewed whenever the CF filter is replaced. Waterdrop counts that layer as a stage of its own: the G5P500A is an 8-stage system, one stage more than the G5P500 without the alkaline layer.

A household that prefers a mechanical faucet, and is comfortable checking filter status on the unit under the sink, will also find the G5P500A a natural match. With its mineral layer inside the CF filter, it keeps a two-cartridge layout, so the mineral step adds nothing extra to the replacement routine.

Within Viomi's own lineup, the RO system with built-in remineralization is the Viomi M1.

FAQ

Will either unit fit beside a garbage disposer?

Width is the dimension that usually decides it, and the Viomi V6 PRO body is 5 inches wide. That slim width is the figure to compare with the clear strip beside the disposer. A disposer hangs from the sink bowl, so the floor beside it is often the clearest part of the cabinet. For the G5P500A, Waterdrop's manual adds 2 inches of clearance around the unit.

What makes a Viomi V6 PRO filter change straightforward?

The cartridges use a tool-free twist-lock design, and both are rated in whole years, 12 months for the PCB filter and 24 months for the RO filter. The orange panel lights give 10 to 15 days of notice before a change is due, so the replacement cartridge can be on hand in time.

What comes in the Viomi V6 PRO box for installation?

The system arrives with its PCB and RO filters already installed, along with the smart faucet and a tee fitting for a refrigerator or ice maker line. The installation video for the model walks through each connection in order, from the cold-water supply to the first flush.

Can the Viomi V6 PRO also supply a refrigerator or ice maker?

It can. The tee fitting in the box branches the purified-water line to a compatible refrigerator or ice maker over standard tubing, so the faucet and the appliance draw from the same system.

Which dimension matters most in a shallow cabinet?

Depth is the one to watch, because under-sink cabinets are often shallower than they are wide. The Viomi V6 PRO body is 16.3 inches on its long side and 12.8 inches high, and on the G5P500A the 2-inch clearance in Waterdrop's manual applies to the front and back as well as the sides.

What Settles It in a Tight Cabinet

A tight cabinet and a household that wants TDS and filter life shown at the faucet point to the Viomi V6 PRO, with its 5-inch-wide body and a pre-filter rated for a full year. Kitchens that want mineral-added water from the RO faucet, and are content with a mechanical faucet and status lights on the main unit, will find that built into the G5P500A's composite pre-filter.