Cold is a possibility, but I don\’t think that\’s what\’s caused this damage; given where you are, unless you\’ve had freak weather conditions in your particular location, it seems the temperatures recently have not fallen below 20 deg C during the day. What has caused it is direct sunlight. These plants do not like direct sunlight even indoors – outside it would be even more damaging, particularly as the plant has probably never experienced any direct sunlight in the whole of its life.
Peace lily is a reliably good low light houseplant, so perfect for your apartment. Trim off the damaged leaves at their bases, the plant will put out more quite happily. These plants do not like to dry out completely and do seem to require a fair amount of watering. That, though, does not mean you should leave it standing in water in an outer tray or container – empty that 30 minutes after watering.
Water when the surface of the compost feels just slightly dry to the touch, and stand the plant away from heat sources such as radiators – the light from any window which does not admit sun, or get any direct sunshine on it other than possibly very early morning or very late in the day, would be the most useful.
I have 3 palants of peace lily, Placed more or less 6 feets away form windows(2windows), I never over water them, I wait for my plants to give me signs of thirst(wilt a little bit),each pot has several drainage holes.
Also the soil is very vell drained. in addition I use water from a tubewell, means no chloride, no chlorine, no fluoride, Nither I have ever used any fertilizer since I brought the home. Humidity levels are also doing fine at 60%. But still their tips are getting brown,. Can some one please tell me, what mistake I am making? Please help this black thumb,