Is tap water bad for Calatheas?

Often, yes. Most tap water contains fluoride, chlorine, and dissolved minerals that Calatheas are unusually sensitive to. These compounds build up in the leaf tissue and burn the edges brown and crispy. Filtered, distilled, or rainwater avoids the problem.

Will crispy Calathea edges grow back green?

No. Once leaf tissue dies it stays brown and will not turn green again. Fix the underlying cause first, then trim the crispy edges for appearance. New leaves should emerge clean.

Should I cut off the crispy edges?

You can. Trimming is cosmetic and does not harm the plant. Use clean scissors, follow the leaf's natural shape, and leave a thin sliver of brown so you do not cut into living tissue and open a fresh wound.

How much humidity does a Calathea need?

Calatheas prefer humidity of 50 percent or higher. Below about 40 percent the leaf edges dry and crisp. A pebble tray, grouping plants together, or a small humidifier all raise local humidity.

How often should I water a Calathea?

Keep the soil lightly and evenly moist, never bone dry or soggy. Water when the top inch feels slightly dry, usually about once a week. Use room-temperature filtered, distilled, or rainwater.

Why does my Calathea get crispy even though I water it often?

Frequent watering with tap water actually speeds up mineral and salt buildup, which is a leading cause of crispy edges. Switch to filtered, distilled, or rainwater and flush the soil to clear accumulated salts.

Why does my Calathea have crispy edges?

Most likely cause

Water quality is the top cause of crispy Calathea edges. Calatheas are far more sensitive to fluoride and chlorine than most houseplants, and tap water delivers both along with dissolved minerals. Those compounds accumulate at the leaf margins and kill the tissue, leaving a thin dry brown band.

You can confirm it by the pattern. Mineral and fluoride damage shows as an even brown rim tracing the outer edge of the leaf, often with a faint yellow halo just inside it. If you water with tap water, this is almost certainly the driver. Switching to filtered, distilled, or rainwater usually stops new damage within a few weeks.

Other causes

These rank below water quality but often stack on top of it.

Low humidity. Edges crisp when humidity drops below about 40 percent. How to tell: the crisping spreads evenly around the whole leaf and worsens in winter or near heating vents.
Underwatering or drying out. Letting the soil go bone dry stresses the roots. How to tell: leaves curl or droop and the soil pulls away from the pot rim.
Fertilizer salt buildup. Excess feed leaves a salt crust that burns roots and edges. How to tell: a white crust on the soil surface or pot rim.
Too much direct sun. Harsh light scorches the foliage. How to tell: crispy patches and faded color on the side facing the window.

How to fix it

Switch your water. Use filtered, distilled, or rainwater at room temperature. If you must use tap water, let it sit uncovered for 24 hours to off-gas chlorine, though this does not remove fluoride.
Flush the soil. Run water through the pot until it drains freely for a minute or two. This rinses out accumulated salts and fertilizer buildup.
Trim the crispy edges. Use clean scissors and follow the leaf's natural shape, leaving a thin brown sliver so you do not wound living tissue.
Raise humidity. Aim for 50 percent or higher with a humidifier, a pebble tray, or by grouping plants together.
Water consistently. Keep the soil evenly moist, watering when the top inch is slightly dry. Ease feeding to quarter strength during active growth.

Cause	Tell-tale sign	Fix
Water quality	Even brown rim, tap water used	Filtered, distilled, or rainwater
Low humidity	Edges crisp all around, worse in winter	Humidifier or pebble tray
Underwatering	Curling leaves, soil pulled from pot	Keep evenly moist
Salt buildup	White crust on soil or rim	Flush soil, reduce feed
Direct sun	Scorched patches facing window	Move to bright indirect light