What are these water lines made of?

I think they are damaged and are not going to not kink. Once that's set in, it will "remember" it. I also think they are weakened because of it. Replace them

I can't tell from the photo, but you may be able to replace the lines with standard braided SS lines from big box.

Disconnect one and take it with you to the store and match for length and for the correct end (looks like both ends are 3/8")

Can't tell, but the marketing says:

"ProMotion® technology's light, quiet braided hose" and

"Includes flexible supply lines for easy installation"

Yea, a little bit TOO flexible.

I bought it from Costco. Here's the model Kohler R75791-2PC-NA All in one kit

On that website it leads to a hose part 1222880-BC which it's unclear if it's the supply line or faucet hose. My faucet hose is great so far.. it's the supply lines they provided

Kohler seems to have a supply line kink problem. Kohler doesn't reveal the material online but the customer suspects it's fiber.

"hose part 1222880-BC which it's unclear if it's the supply line or faucet hose"

That's the hose.

This is 100% installation error.

Thank you.. definitely will call Kohler tomorrow since they're open on Saturday. If no luck, I'll go to a big box store. One plumber said he carefully clamped the kink and it formed back.

Kohler reps on the internet claim running water through it will form it back but I doubt it.

Mine came out of the box seemingly fine, it was when I had to make a loop that it kinked. Already installed the sink and it looks good but I didn't like that only 2 sides had U-channels for clamps. But it was a good price at Costco.

Jospeh Corlett LLC.. how would you avoid making a loop? Shouldn't good material withstand responsible looping? Even dishwashers have high end loops.. just sayin'

Here's the thing from my perspective:

-Broken supply lines cause a lot of damage.

-Kinks like this are typically significantly weakened.

-It's not worth chasing down the part and messing with warranty, etc. if it's an easy replacement from big box.

-Just replace it. Get it longer if you want to do a 360 loop. Otherwise do an S curve.

The part number is 1202078 which has apparently been replaced by 1207169.

But I'd measure the lengths of the supply lines needed and take a kinked line to Home Depot to see if you could find a replacement.

You can get these lines in different lengths. And they should just be standard parts. Measure how long you need it to be and buy from your local building supply store or even just from Amazon. Life is too short to agonize over problems that can easily be fixed for a tiny amount of money. And doing this correctly is so much cheaper than dealing with a leak down the line.

I see some listings for less than $10, but most are between $10 and $20. But I can't quite tell from the pictures which model you need precisely, so I can't make a suggestion.

If you pick the correct length, there shouldn't be an issue with kinking. Incidentally, the same is true when hooking up a toilet to the water supply. Buy the correct (length of) supply line.

That would be ideal to get the exact length, so I'll also stop in the local Ferguson's supply to see about that. They have better customer service than big box stores.

"That would be ideal to get the exact length, so I'll also stop in the local Ferguson's supply to see about that"

You just need to measure the distances between the two valves and the two copper pipes to which the supply lines are connected, and then buy supply lines at least those lengths with connectors on both ends that match those of the kinked supply lines you own.

Thanks wdccruise, M, etc. I'll have to go to a specialty store or order online. Big box stores don't have the length I need to avoid looping or bending.

Stax, we agree on getting the right length of supply line but not on big box vs specialty stores. SS's give me better feedback, advice, networking and results. Sometimes it's a long term thing. It's just like on Houzz, you have to ask the right people and be patient and you get the best answers.

I agree with you in principle. I like my specialty stores for when I need them.

But that's not true for commodity items that need to be ordered in unusual sizes or quantities. Your specialty stores isn't going to provide any added value, but they'll still charge their usual mark up.

I'm not going to my boutique deli store, when I need 50 lbs of flour. I'll go to Costco instead. If I need a particular flour with precise specifications, then I order directly from King Arthur. And only when I need to try different international brands of Italian 00, German 630, and French T150 flour would I check the specialty store.

Same for your home repair supplies. If the big box store doesn't carry it, order from Amazon. It's good enough and you're more likely to get the right part then when going through a middle man. Alternatively, ask your plumber. He can get the perfect fit from his supply house. And if it didn't fit, he'll come back another day

Get lines that are just the right length or if that isn't possible, extend these lines long enough that they can be looped withou kinking.

The kinks are from installation error. I am assuming that you installed these DIY because of the Costco kit. You do not need to contact Kohler or go to a plumbing supply house. You can go to the big orange, blue, or green store. These are simply s.s. braided faucet supply connectors.

They come in different lengths: 9", 12", 16", 20", 30", 36". They also have some others that do not have the S.S. braided cover, but these are better and only cost a buck or two more. Your cost should be around $5 for each connector. It appears to be a 3/8" compression + 1/2" FIP, which is what the 'hoses' will be as standard. Measure the distance and you only put in loops when you are just short and cannot have an 'S' curve. When I have a faucet install, I typically have a few lengths on hand because you also have to negotiate the pull-out hose, DW lines, etc.

Here's how I think the installation error occurred: You seated the nut barely by hand, then used pliers on the nut to tighten the whole length of thread. What you will notice is that the 'hose' might turn with the nut while you are tightening the nut, and that twists the 'hose' which allows kinks to occur.

To prevent this, you need 2 tools and two hands: as you are turning the nut by hand tightening, you hold the crimped end of the 'hose' with your other hand to keep it from twisting. That will ensure the 'hose' is draped without twists. Same goes while tightening with tools, hold the hose so it does not follow the twists of the nut. The better tool is a crescent wrench on the nut, and an adjustable plier if needed to lightly hold the crimp on the 'hose' AND to hold the stop valve to prevent the stop valve from moving as you torque the nut with the crescent wrench.

Also, there should be a weight on the pull-out sprayer hose, and make sure that when it falls down it does not have to knock against the stop valve and faucet supply lines, as that may lead to leaks in the future.

3onthetree, excellent info and explanation. I will keep all that in mind. I agree on the weight for pull out hose. I can barely fit my body in there and needed to temporarily remove it