
I couldn’t find the figures for the uk but around 1.6 Billion pens are thrown into landfill in America alone. Granted that this also includes ballpoint type pens.
Don’t throw away those permanent markers, if the felt nib is good, you can refill them!
I’ve refilled all sorts of permanent pens and continued to use them many times over. Even the cheap ones which you imagine are single use, the cap can be removed and they can be recharged.
Refilling Common Pens.

I’ve done extensive research on what inks will work with different colours and different brands of pens. These are now available to buy on the website. They come in 10ml refill bottle which should last quite a long time.
Pull off the cap or unscrew to expose the internal fibre tube of the pen and simply refill.
Use the ink sparingly and carefully. Ink can be cleaned and removed with Mentholated Spirit.
To refill the Pica Ink extract the fibre core by pushing the metal tube backwards and pulling out the fibre core, insert the refill nozzle and top up by carefully pumping the refill bottle. When sufficient ink has been added refit the fibre core. As shown in the gallery below.