Countertop vs Under-Sink RO for Renters

Short answer: if you cannot drill, or you do not want a lasting change to the sink, buy a countertop RO or a pitcher. The Waterdrop C1SL plugs in and has no faucet hole. The AquaTru Carafe is the countertop RO whose public data sheet names an IAPMO listing. The G3P800 and the G3P600 are under-sink systems: each box includes its own faucet and a drain saddle. That is a permanent install. Whether a lease allows it is not something this page can answer.

Published November 3, 2026. Figures are from Waterdrop's US C1SL, G3P800, and G3P600 pages, from AquaTru's Carafe performance data sheet 10.24.R3, and from the Amazon listings linked below, all read that day. The C1SL product feed showed the variant in stock at $269. The G3P800, G3P600, AquaTru Carafe, ZeroWater pitcher, and PUR faucet-mount listings were in stock the same day. We have not installed any of these, and we don't run a lab.

What "under-sink" actually changes

An under-sink RO in this comparison is not a clamp-on filter.

Waterdrop G3P800, read November 3, 2026:

• Spec table: 800 GPD, pure-to-drain 3:1, electricity required, indoor use
• In the box: the system, an RO faucet, a feed-water adapter, and a 1/4 inch drain saddle
• Waterdrop's page calls the install a 30-minute DIY job. The parts list is still a faucet and a drain connection
• Certification line on the page: IAPMO R&T to NSF/ANSI 42, 53 and 58 for the claims on the performance data sheet, plus NSF/ANSI 372 for low lead

Waterdrop G3P600, same day:

• Spec table: 600 GPD, pure-to-drain 2:1, electricity required
• In the box: an RO faucet and a drain saddle, same idea as the G3P800
• The FAQ says it needs a drainpipe nearby and an outlet under the sink

Both are tankless. Both leave hardware attached to the plumbing when you move, unless you remove it and close the holes. The G3P800 vs AquaTru page is the under-sink versus countertop comparison once an install is actually an option. The G3P800 vs G3P600 page is the flow and drain-ratio choice between those two tankless units.

We are not describing landlord-tenant law, and we are not saying a lease forbids or allows drilling. Read the lease. If it is silent, ask the landlord before you cut a hole. A written yes is the only permission that counts, and it is theirs to give.

Countertop RO: no faucet hole

Waterdrop C1SL. The US page we read lists a 7-stage countertop RO, 75 GPD, a 3:1 pure-to-drain ratio, and a size of 11.7 by 8.3 by 13.7 inches. The FAQ says you do not drill: plug it into an outlet. There is no drain saddle in the box. You fill a feed tank by hand. The spec table on that page does not name an NSF, WQA, or IAPMO certification. Waterdrop's marketing line says the system reduces TDS, PFOA, PFOS, chlorine, lead, and adds minerals. That list is the manufacturer's, not a certificate. Our C1SL review records the manual limits we read on October 20, 2026: municipal tap water and feed TDS under 500. We did not re-open that manual on November 3.

AquaTru Carafe. The Amazon listing we opened (ASIN B0C36HFC5Q) is the Glass Carafe Alkaline countertop RO. It was in stock. It plugs into a wall outlet. Nothing in that listing is a drain saddle or a sink hole. AquaTru's Carafe performance data sheet 10.24.R3, which we opened the same day, says models AT100, AT110, AT120, AT130, and AT140 are certified by IAPMO R&T to NSF/ANSI 42, 53, 58, 372, and 401 for the claims on that sheet. The sheet also prints a daily production rate of 35 GPD and an efficiency rating of 63 percent. Details, including the fluoride row, are in the AquaTru review and the fluoride guide.

Counter space and an outlet are the real limits. The C1SL is about 14 inches tall. You take either unit when you move. Neither treats the shower.

Pitcher and faucet mount, if RO is more machine than you want

A pitcher is not reverse osmosis. It is the option with nothing to plug in and nothing to unscrew from the faucet.

The ZeroWater listing we opened is the 10-cup pitcher, model ZP-010. Amazon's page calls the installation type freestanding. It is a pitcher with a TDS meter, not a whole-house system and not an under-sink RO. The listing says the 5-stage filter is IAPMO certified to reduce PFOA/PFOS, lead, chromium, and mercury. It does not name fluoride. It was in stock. The pitcher guide compares it with Brita and Clearly Filtered.

The PUR PLUS faucet mount, FM-3700 screws onto a faucet that has an external aerator. PUR's listing says no tools, that it is not for pull-out or handheld faucets, that the filter lasts up to 3 months or 100 gallons, and that it is WQA certified to reduce lead and NSF certified for microplastics, chlorine, and other listed substances. PUR also says it does not filter microbes. It was in stock. You can take it off when you leave. It is not an RO system.

A standard carbon pitcher is a taste-and-odor filter unless its own data sheet names the contaminant you care about. Do not read "filter" as "fluoride" or "TDS."

Which one to buy

Choose the C1SL if you want reverse osmosis, you cannot add a faucet hole or a drain saddle, and you accept a US product page that does not name a certification. Confirm the water is municipal and, if you can, that TDS is inside the manual limit recorded in the C1SL review.

Choose the AquaTru Carafe if you want that same no-plumb setup and you want the IAPMO listing on the Carafe sheet. Read the sheet for the contaminant you care about before you buy it for that contaminant.

Choose the G3P800 or G3P600 if the lease allows a faucet hole and a drain connection, you have an outlet in the cabinet, and you want water from a dedicated faucet instead of a tank you fill by hand. Between those two, the G3P800's published ratio is 3:1 and the G3P600's is 2:1. See how RO wastewater ratios work.

Choose a pitcher or the PUR faucet mount if you want something smaller, cheaper to try, and easy to remove. Expect less than an RO membrane. The broader shopping list is the rental-house filter page.

Frequently asked questions

Can a renter install an under-sink reverse osmosis system?

The machines can be installed. The G3P800 and G3P600 each ship with a faucet and a drain saddle, so the job cuts a hole and ties into the drain. Your lease is the document that says whether you may do that. We do not interpret landlord-tenant law.

What is the no-drill reverse osmosis option?

A countertop unit. Waterdrop's C1SL FAQ says it does not need drilling. The AquaTru Carafe is the countertop RO with the IAPMO listing described above. A pitcher is the option with no RO machine at all.

Does the C1SL need a drain line?

No. Waterdrop lists a 3:1 pure-to-drain ratio and a plug-in countertop unit. You fill the tank. An under-sink system uses a drain saddle. The C1SL does not.

Is a pitcher the same as reverse osmosis?

No. The ZeroWater ASIN on this page is a 10-cup pitcher. It does not replace the reduction claims on an RO performance data sheet.

Related guides

• Best water filter for a rental house
• Waterdrop C1SL review
• Waterdrop G3P800 vs AquaTru
• RO wastewater and drain ratios
• Renter-friendly filters, no drill