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How We Plumbed Our Sink with an Extra Deep Countertop


When we decided that we’d be using extra-deep 24″ upper cabinets in the laundry room, we also realized that in order to maintain a functional countertop depth, we’d need to cheat the base cabinet forward by 8″ to maintain good working proportions. We went back and forth on how to accomplish this task, but eventually, we ended up building a simple 8″ box frame to give the base a sturdy way to attach to the wall… and all was right with the world. But once it came time to plumb the sink, we had to find a work-around that would ensure access to the water supply connections and also allow everything to drain back into the wall properly.


1.5″ Waste arm (A)
1.5″ 90-degree elbow (B)
2 x 1.5″ Extension tube (C – and another after (D), but not pictured below)
1.5″ P-trap (D)
Plumber’s putty
Sawzall w/metal or plastic cutting blade
Drill with 1.75″ hole saw
Access panel
Construction adhesive



In order to reach the water shut off behind our base cabinet, we needed to install an access panel. Normally, the water shut off would be on the inside of your cabinet, but because we cheated our cabinet 8″ from the wall, this is a simple workaround! After tracing the inside portion of the cover, I used my jigsaw to cut a 1/2″ outside that line, then glued the “frame” of the panel in place with construction adhesive. The panel was positioned just to the left of the water shut off – but still within easy reach – which would allow me to plumb the sink properly.


Now on to plumbing up the drain. PVC drain line basically works like the tubes on a hamster cage, but with gaskets to eliminate leaks – and hopefully, without all the hamsters.  The gaskets have a convex shape, which mates to the concave shape of the pipe junctions and is secured by a threaded ring. No tools required!


Below, you can see those supply and waste lines that would typically inside the cabinet in a standard installation (where the cabinet rests against the wall) are 8″ behind the cabinet in our case. I used our drill and a 1.75″ hole saw bit to cut a nice round hole, then inserted a simple 1.5″ extension tube to move the wastewater connection back inside the cabinet.


Once I reached this point, it was time for a quick – completely unplanned and 100% our fault – sink modifying interlude! When it came time to install the sink below our butcher block countertop, we realized that we didn’t follow the cardinal rule of construction – measure twice, cut once. Kim mentioned a little while back that we had failed to account for the full depth of the lip of our under-mount sink when we drilled the faucet hole in the countertop. This moment of realization hit us hard (during a dry fit, at least!), but we were determined to find a solution. In this house, solution = more power tools. This case was no exception.

Hopefully you’ll never, ever run into this issue, but just in case, here’s how we modified our cast iron sink with success. While I held up the sink from below our counter top, Kim used a permanent marker on the sink rim to trace what was visible from the sink hole. The goal? We needed to eliminate this part of the sink.

In an effort to keep the porcelain coating on the cast iron sink from shattering, I used a carbide tile-cutting bit in my rotary tool to score a line in the enamel and keep destruction to a minimum. Side note: This scenario was (hopefully!) unique to us, so I left these tools below off of the supply list, above. 


Once the porcelain was completely scored through and the cut edges were smoothed, it was time to call for heavy artillery – my angle grinder! I slowly ground away the cast iron from the half-moon shape that I’d scored. After getting past the nerves involved with attacking a perfectly handsome sink with a 10 year old $30 angle grinder, the results were far better than we could have anticipated.


Once the sparks were done flying, the end result was exactly what we needed. (The black marks you see on the bottom of the sink were just metal dust, thank goodness.) The photo below is taken from underneath the sink, looking up toward the underside of the countertop; you can see how our initial lack of math necessitated cast iron sink surgery. All said, we’re really happy with the end result!


After dealing with the sink debacle, we carefully secured and caulked the sink before moving on to the sink strainer basket. Per instructions, I rolled a nice fat worm of plumber’s putty around the edge of the basket, plopped it into place and tightened it up from the bottom. When used properly, a fairly uniform amount of putty should squeeze out into the sink opening as seen in below-right.


Kohler sinks utilize an ingenious set of fasteners that require no specialty tools to secure the basket strainer to the sink drain hole. Simply tighten the large threaded ring by hand, then tighten the screws evenly to complete the job. When done, the excess plumber’s putty peels right up!


The angled waste arm included a stubby little tail piece (seen blurry in the foreground) to allow for maximum clearance below the sink, so that went in first on the sink end. On the drain end, I worked backwards and installed the P-trap at a 90 degree angle to again provide maximum space inside the cabinet. At this point, I also drilled another small hole with our hole saw to allow the hot and cold supply lines from our faucet to make their way to the in-wall connections.


The whole goal here is for everything to meet up at and slip together without any tight angles or “stress” on the piping. I like to build the system without gaskets or threaded rings first to allow for easy slip fitting and any necessary adjustments. I simply mark my lengths with a sharpie, and excess can be cut with most any saw. I like a reciprocating saw with a metal-cutting blade to eliminate rough edges or burrs on the plastic, and any rough spots can be smoothed out with fine-grit sandpaper.


Once I was happy with all of my lengths, I did a final dry fit to ensures aligned properly. I also made sure that all of my pipes had a gentle slope away from the sink to avoid any standing water in the drain piping.


I was happy with how the pipes came together, so I disassembled everything, installed the green gaskets at all of the junctions, and I tightened everything by hand. Again, no tools required!


The final step here is the best indicator of your work thus far. At the end of every plumbing project, I turn on the water and let it drain through the sink for a few minutes. I like to keep a few towels on hand and place a bowl under the drains just in case there is a leak somewhere. If all was done well, this step will be fairly uneventful!


With the exception of a few stressful moments, we couldn’t be happier with how the whole sink area came together, but let me take a moment to talk about the real stars of the show – our sink and faucet! We installed the Porto Fino sink from Kohler in Sea Salt, which has a subtle off-white granular look and works really well with the cream-colored ostrich wallpaper. Our sink is paired with a chrome Purist faucet, which has a pullout feature that is always nice to have.


We’re thrilled to have a finished, functioning sink in the laundry room, which has been great for so many reasons – treating a quick stain before a load of wash, rinsing puppy paint palettes and filling Libby’s water bowl. Kim photographed the laundry room a few days ago, so the next time we share this room, it will be a completed room!

What sort of self-induced plumbing challenges have you all faced in your spaces? We’d love to hear about your creative solutions!

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  • Stacy G.12.13.16 - 6:56 AM

    Oh my. This is a big topic in our house which is over 130 years old. We have uncovered all sorts of creative solutions in this house, but we have not done any of them for ourselves yet. The general rule with the plumbing in this house is, “Do NOT touch it.” As soon as we mess with anything, it springs a leak. :D

    Most of the creative plumbing in our house revolves around parts. They used a similar, but incorrect part because an original part was not available or could not be found at the time. Since the new part is not quite right, it fails at unexpected times.

    We will get to it all in time, but for now, we keep our hands off unless we have an emergency. LOL

    Great solution for your sink. It looks terrific!ReplyCancel

    • Kim12.13.16 - 8:55 AM

      Yikes! You can’t mess with plumbing parts – the part you need is the part you get. No substitutions! Luckily, a lot of the creative “solutions” we’ve found in our home haven’t been plumbing related… knock on wood!ReplyCancel

  • Julie Marquez12.13.16 - 7:46 AM

    We are putting in a deep counter in our kitchen at the sink wall, so this was a perfect tutorial for my situation. Your project turned out beautiful!ReplyCancel

    • Kim12.13.16 - 10:47 AM


    • Ryan12.13.16 - 2:55 PM

      We might be doing the same thing. The vent pipe for the kitchen sink is on the interior of our masonry wall and I want to put an under counter fridge in front of it. So i might need to float the sink cabinet forward to match the fridge depth and have been thinking about plumbing solutions. We have the added issue of the plumbing being on an exterior wall though so I want to make sure to keep the water lines inside the cabinet as much as possible to reduce the risk of freezing in the winter.ReplyCancel

  • Sammy12.13.16 - 10:37 AM

    I love love love this. I love your blog, me and my boyfriend read it all the time to get ideas for our renovation. We loved the butcher block post because we will be doing that this week!ReplyCancel

    • Kim12.13.16 - 10:48 AM

      Aaah, so sweet. Good luck, Sammy! Your kitchen remodel is looking niiiice.ReplyCancel

  • Julia at Home on 129 Acres12.13.16 - 10:51 AM

    What is the coating on the wallpaper? I’m not a tidy laundress–or DIYer–and I’d be concerned about getting spatters on that beautiful paper. I know some wallpapers have a glossy coating that would wipe off fairly easily, but this looks quite matte.ReplyCancel

    • Kim12.13.16 - 10:57 AM

      It is pretty matte, so is it a little risky to not have a backsplash? Probably. But for such a low use sink, we’re okay with that. :) Wallpaper gets soaked during the installation process, so we figure that splashes of water from time to time won’t hurt it!ReplyCancel

  • Marti | Project Palermo12.13.16 - 7:22 PM

    I can imagine how crestfallen you must have felt to discover the faucet hole error! Nice work with solution – scoring the enamel is really clever.ReplyCancel

    • Kim12.13.16 - 9:55 PM

      Our hearts sank to our stomachs. Thank GOODNESS our plan worked! Thanks, Marti!ReplyCancel

  • Josh @ The Kentucky Gent12.13.16 - 10:30 PM

    You two are champs at rolling with the punches – I don’t think I would’ve handled having to tackle that sink surgery quite so calmly. Looks incredible though!ReplyCancel

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