Every other big-box retailer on this site — Home Depot, Lowe’s, Costco, Menards — sells tankless water heaters as something you can physically find on a shelf or ask an associate about. Walmart doesn’t work that way for this category. It’s the first retailer-vein entry here that’s genuinely an online-catalog play rather than a walk-the-aisle experience, and that changes what “buying at Walmart” actually means for this kind of appliance. Here’s what’s actually listed, why the Rheem model names look different than what you’d see at Home Depot, and what the return process looks like if the unit doesn’t work out.
What’s actually listed, and who’s selling it
| Rheem RTEX (electric) | EcoSmart (electric) | Rinnai RU199iN (gas) | |
|---|---|---|---|
| Naming | Real pro-channel RTEX names | Standard ECO-series naming | Standard Sensei-collection naming |
| Typical seller | Walmart-fulfilled | Walmart-fulfilled | Often Marketplace (third-party) |
| Price range seen | ~$265–$642 | ~$183–$423+ | Varies by seller, not fixed-catalog |
| Local pickup | Rarely available | Rarely available | Rarely available |
Prices and listings per Walmart.com as of September 2026; marketplace pricing and stock change without notice and vary by seller.
By the numbers
- $265 vs. $549 — Walmart’s listed price for the Rheem RTEX-13 (13kW, point-of-use class) versus the RTEX-24 (24kW, whole-home class), both under the real RTEX pro-channel model name rather than a retail-renamed equivalent. — per Walmart.com listings
- $1,068.15 to $641.59 — the RTEX-27’s original list price versus its current discounted price on Walmart.com, a roughly 40% markdown on the top-output RTEX model (though it was out of stock at the time of this check, a common pattern for Walmart’s larger appliance listings). — per Walmart.com listing history
- 30 days — the standard Walmart.com return window, but with a carve-out: major appliances aren’t accepted as in-store returns at all, so a tankless water heater has to go back through Walmart’s online or Marketplace return process instead of a local drop-off. — per Walmart’s Major Appliances purchase-and-returns policy
1. Rheem RTEX-24 — Best if You Want the Real Pro-Channel Name
Rheem RTEX-24 240V Electric Tankless Water Heater
- Listed under Rheem's actual RTEX-24 model name — the same designation a plumber sources through wholesale supply — rather than the RETEX/ECOH retail naming Home Depot uses for its Rheem catalog, per our Rheem lineup guide.
- 24kW puts it in whole-home electric territory for warmer climates or a 1–2 bathroom household; confirm your incoming groundwater temperature against Rheem's GPM tables before assuming it covers simultaneous use.
- No local pickup on most listings — budget for shipping lead time and freight-style delivery rather than same-day pickup.
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2. EcoSmart ECO 27 — Best for Higher Simultaneous Demand
EcoSmart ECO 27 240V Electric Tankless Water Heater
- EcoSmart's self-modulating technology only draws the power needed for the current demand, which is why it shows up across multiple retailers at a similar spec-for-dollar rate — see our EcoSmart lineup guide for how the ECO series scales by kW tier.
- 27kW requires a dedicated high-amperage circuit (verify against your panel capacity before ordering) — this is whole-home electric territory, not a point-of-use add-on.
- Sold and fulfilled by Walmart on most listings, which keeps it inside Walmart's standard (not Marketplace) return process if it doesn't work out.
What shopping at Walmart is actually like for this category
- No aisle to walk. Home Depot, Lowe’s, and Menards all put tankless water heaters on a plumbing-department shelf you can inspect before buying. Walmart’s listings overwhelmingly show pickup as unavailable, which means this is a ship-to-home purchase from the start — factor in delivery lead time, not a same-day install.
- Walmart-fulfilled and Marketplace listings are mixed together. Several Rheem RTEX and EcoSmart electric models ship and are sold directly through Walmart’s own catalog. Some gas units, including Rinnai’s RU199iN, are more commonly listed through Walmart’s Marketplace program, where a third-party seller controls price and part of fulfillment — check the “Sold & shipped by” line before assuming every listing behaves the same way.
- Major appliances can’t be returned in-store. Even though standard Walmart.com merchandise gets a 30-day return window, that doesn’t apply the same way to a category this large — returns route through Walmart’s online or Marketplace return process, not a local customer-service counter, so plan on arranging your own return shipping if the unit needs to go back.
The bottom line
Walmart is the first retailer on this site where the honest pitch isn’t “here’s what’s on the shelf” — there isn’t one for tankless water heaters. What it does offer is Rheem’s real RTEX pro-channel model names at competitive prices (RTEX-24 around $549) instead of the retail-renamed RETEX/ECOH line Home Depot carries, plus EcoSmart’s standard ECO-series lineup, both largely Walmart-fulfilled. Gas units are more of a mixed bag, often listed through Marketplace sellers rather than Walmart directly. If a physical aisle and an in-house install-booking flow matter more to you than the RTEX naming, our Home Depot and Lowe’s guides cover that experience; for every brand ranked side by side regardless of retailer, start with our best tankless water heater roundup.