Sometimes a shower door gives you a clue before it starts leaking badly.
Close it and take a proper look. The gap along the bottom may be slightly wider at one end, or two magnetic seals that should meet neatly may only touch at the top.
We are talking about a few millimetres here. Easy to miss, but enough to change how well the seal works.
Before replacing the seal, or deciding the whole shower screen has had its day, check how the door is actually sitting when it is closed.
Check the door before blaming the seal
Start with the gap along the bottom and down the sides.
If one side is clearly wider than the other, the seal may only be part of the problem. A hinge can loosen over time, and a door can drop slightly after years of use. Sometimes the screen was never perfectly aligned in the first place.
A longer or thicker seal will not necessarily fix that.
If the gap is around 3mm at one end and 8mm at the other, the same seal has to deal with two very different spaces. It may be squashed against the tray at one end and still miss it at the other.
Sorting out the door position first usually gives you a much clearer idea of what, if anything, needs replacing.
A yellow seal is not always a failed seal
Clear shower seals often discolour with age. That alone does not tell you much about whether they still work.
Give the old seal a quick feel. Has it gone hard? Is it cracked, loose on the glass, or permanently bent out of shape? Then close the door and check whether it still reaches the tray or the other seal properly.
Magnetic seals can be a little trickier.
Two glass panels may have been designed to meet at 180 degrees, but a small shift in one panel can change the way the magnets line up. From the front, everything may still look almost straight. Up close, the seals might meet firmly at the top and leave a few millimetres of space lower down.
That is where choosing a replacement purely by appearance can go wrong.
SIMBA Seals UK looks at details such as glass thickness, the actual gap and how the door meets when closed when helping customers narrow down replacement shower seals. A tiny difference in the way the glass sits can be enough to make one profile a better fit than another.
Most replacement choices come down to a few measurements
The number of shower seal shapes online can make a simple job look more complicated than it is.
You do not need to learn what every profile is called. Start with the basics: where the seal sits, how thick the glass is, how much gap needs to be covered when the door is closed, and whether the old seal clips onto the glass or fits into a frame or channel.
If you are not sure where to measure, the Shower Door Seal Learning Centre has a straightforward guide to the basics.
No part number on the old seal? A clear photo of the end profile can be more useful than the front view. Add the glass thickness and gap, and it becomes much easier to rule out replacements that only look similar in a product photo.
Sometimes the water is coming from somewhere else
A door can be straight and the seal can be making contact, yet water still appears nearby.
In that case, look at the fixed edge of the glass and the silicone around the shower tray. Water can run down a fixed panel and collect by the door, making the bottom seal look guilty when it is not.
Dry the area, run the shower briefly and watch where the first trace of water appears.
If the problem is a worn seal, a slightly dropped door or a small section of failed sealant, replacing the whole shower screen is probably unnecessary.
A full replacement makes more sense when the glass is damaged, the frame or fixings have failed, or the door can no longer be adjusted back into a normal position.
