Chhath comes in Kartik, when the Patna mornings finally turn cold. You are standing in the Ganga at Digha ghat before the sun is up. Water to your waist. You lift the daura, you give arghya to the rising sun, and the whole ghat is doing the same. The saree you have on is new, or it is last year's, kept for exactly this morning. By the time you climb back up the steps, it is soaked past the knee and heavy.
That river water is not clean the way your tap at home is clean. The Ganga at Patna carries silt. Fine grey-brown mud, so fine you cannot feel a single grain of it, and right now it is sitting inside every thread of your saree from the hem up.
You do not wash it at the ghat. You walk home. Through the crowd on the ghat road, past the stalls, the wet saree still on you or bundled in a bag. It stays wet for an hour. Two hours. The arghya, the prasad, the thekua going around, and nobody is thinking about the clothes yet.
By then the silt has started to dry.
The brown line at the hem
Watch what silt does as it dries. It goes stiff. It pulls to the lowest, wettest part of the cloth and leaves a faint tide line across the border, brown against the red or the yellow. Your first instinct is to rub it. That is the wrong move. Dry silt is basically fine grit, and rubbing it grinds each grain deeper between the fibres. You are not lifting the dirt. You are sanding it into the saree.
A cotton Chhath saree is not built to take that. The threads are soft. Once the silt is worked in, that grey shadow stays even after the cloth looks dry and folded.
The bigger mistake is the almirah
Here is the one that actually costs you the saree.
The Chhath saree is special. You do not treat it like a normal saree. You keep it for next year, sometimes for many years. So it gets folded and put away in the almirah, and in the rush of a four-day festival it often goes in before it is fully dry. Damp at the border. Damp in the pleats where the sun never reached.
A cotton saree packed damp into a shut almirah, in Patna, for a whole year, grows mildew. Quietly. You open it next Kartik and there is that musty smell and a scatter of grey spots that no wash takes out. The saree you handled as sacred is the one you killed by folding it wrong.
What actually gets the silt out
Rinse before you do anything else. Plain cold water, a lot of it, and let the silt float and run out on its own. No soap yet, no scrubbing. You want the loose mud gone before it can dry and set. Do this the same day, not the next morning.
Then a gentle wash. Cotton does not want a hard hand or hot water. Mild detergent, soft handling, and rinse until the water runs clear and not cloudy.
Then dry it fully. All the way. A full day in the Kartik sun, and go back and check the thick parts, the border and the folded pleats, with your hand. If it feels even a little cool, it is still holding water. Only fold it when there is no cold and no damp left anywhere. Store it dry, in a dry almirah, and it will be there for you next year.
The new saree has its own problem
If you bought it new for Chhath, wash it once before you wear it into the water. New cotton comes with starch and sizing to make it look crisp on the shelf, and loose dye that has not been rinsed out. Wear it straight from the shop fold into the Ganga and the starch traps silt faster and the colour can run onto your skin and your other clothes. One wash before the ghat and it behaves.
The four days are not for scrubbing
Chhath is standing in cold water at dawn. It is cooking prasad on a clean chulha. For the vratti it is days with no food and no water. The saree soaked in Ganga silt is the last thing that should be waiting for you at midnight.
DoorWash picks up from your door and brings it back clean, dried right through, and folded. You give the sun your arghya. Let us handle the saree.