That looks like one of two things: too little water or too dry air. If it's indoors and anywhere near a heater or a/c vent, that's your problem.

You don't root these plants in water, you propagate them by division when they get pups. You can grow them from cut-up pieces of leaves, but you won't get the same plant. That particular plant can only be propagated from division, or you'll lose those lovely yellow stripes on the sides.

What kind of soil do you have it in? Sansevierias need very well-drained soil, in fact, I grow mine in 50/50 potting soil and perlite. You can even grow them in cactus soil.

They need to dry out completely between watering, but they do need water, and when grown indoors, they especially need humidity. I usually grow mine in clay pots (hard to overwater a clay pot) and water very well when they are completely dry.

The fun thing about these is that you can trim off those brown edges for the sake of looks. You can even shape the leaf ends to look more natural. The cut edges will callous over.

Also remember that eventually, outside leaves of these plants will die. It's just what they do, like some plants dropping bottom leaves to grow.

Hope this helps.

How strong is the root system? Is the soil draining properly? How much water do they get?

They are outside, I live near the ocean so they get plenty of humidity. We've had a very dry winter, I've had to water them occasionally, but not too much. There was another variety in the pot that had horizontal stripes. That was the only one affected at the time, so I pulled all those out, and just left the ones with the yellow leaf edges. Now they are getting the dry spots.

@dirtygardener: I think these can be propagated in water. I only learned that after cutting off some leaves and putting them in a narrow vase of water in the house. After a month or so I noticed the leaves all had roots on the bottoms.

@echobelly do you have salt in your irrigation water? Are you close enough for them to get salt spray?

Yes, the leaves will get roots, but the plants that eventually grow from them will not be like the ones you have. They will be regular green sansevieria. Trust me on this. This particular variety will not grow true from leaf cuttings, but you'll get lots of nice green ones!

Sansevieria only have moderate salt tolerance.

ufdcimages.uflib.ufl.edu/IR/00/00/23/92/00001/WO01200.PDF

Not close enough for salt spray, not sure about my irrigation water, but I don't water them much, rely on the rain. I've had these for years, and just suddenly this started happening. Another pot nearby isn't affected at all, which is making me think it may be a fungus or virus in the soil.

The circular spots do look like some sort of lesions...

Even if you are NOT getting salt spray, you are probably getting salt on the leaves in our strong winds and storms. I use to get damage on my rose leaves after storms or winds. It was suggested to me that even if we have had rain to get out the hose and wash the leaves, both upper and lower sides..... My rose leaf damage was browning like that.... but i don't know about your plant, but if someone thought it might be salt I thought I would let you know about my salt problem.... I am on the intra costal, but my roses are set way back and never get spray on them, but they do get salt because it is carried on the wind.... good luck

@sharon2079 I don't think it's salt, as another pot of Sanseviera on the other side of the walkway, literally 3 ft. away isn't affected at all. That's why I'm leaning towards thinking it's some sort of fungus or virus in the soil.