Drawing of a cat on a toilet reading

The Zero Waste Cat Litter Conundrum

There’s noth­ing like shar­ing your home with a feline friend but, just like us, cats are not zero waste. One area in which it’s easy to improve the car­bon paw­print of your fur­ry companion(s) is the lit­ter box.

Whatever you do, don’t flush!

Tox­o­plas­ma gondii is a par­tic­u­lar­ly dis­taste­ful-sound­ing par­a­site that may be present in your cat’s feces. If your cat is an out­door cat or goes out­doors from time to time, then it’s much more like­ly to car­ry this par­a­site. Reg­u­lar waste­water treat­ment can­not remove tox­o­plas­ma gondii and so it can end up in our water sup­ply. 

surprised cat on a toilet

The par­a­site can cause prob­lems for peo­ple with weak­er immune sys­tems or con­gen­i­tal birth defects in unborn babies. If you’ve ever come across the rec­om­men­da­tion that preg­nant women steer clear of the cat lit­ter box, now you know that the warn­ing has a real med­ical basis! Tox­o­plas­ma gondii also con­tributes to the deaths of wildlife as the tox­in gets into water sources such as streams and rivers. 

You can get your fur­ry friend test­ed for the par­a­site by a vet, but if you haven’t yet done this, the best course of action is to nev­er flush cat lit­ter down the toi­let.

Biodegradable bags

Whether we’re talk­ing about using lit­ter tray bags or not, at some point in the process some form of petro­chem­i­cal bag is like­ly to rear its ugly head. There’s no per­fect solu­tion to this prob­lem, but the best and most prac­ti­cal choice so far is to use biodegrad­able lit­ter tray bags.

Go for ASTM 6400-cer­ti­fied biodegrad­able bags, most often made from corn­starch, in order to be sure that your bags will actu­al­ly decom­pose. Oxo-biodegrad­able bags (ASTM D6954) are a much less clear-cut, plas­tic-based alter­na­tive that is best avoid­ed.  

P.S.  You’re also like­ly to save your­self some plumb­ing repair costs by bag­ging rather than flush­ing your cat lit­ter!

The truth about biodegradability

Remem­ber that whether a “biodegrad­able” bag is made of corn­starch (good) or plas­tic plus addi­tives (less good), biodegrad­abil­i­ty does not mean that you can throw a bag out and trust that it will mag­i­cal­ly dis­solve into it’s sur­round­ing envi­ron­ment. 

The major­i­ty of biodegrad­able bags end up in land­fill, where they are quick­ly cov­ered by lay­ers of oth­er rub­bish that deprive them of the sun­light and air they need to decom­pose. The only way to ensure an envi­ron­men­tal­ly-friend­ly end for your biodegrad­able cat poop bags is to com­post them (more about that below). 

Box matters

Many, our­selves includ­ed, fall into the trap of think­ing that a lit­ter box is just a rec­tan­gu­lar piece of plas­tic. Sure, there are fan­cy lit­ter robot sys­tems out there that tend to look a lit­tle like some­thing out of Encoun­ters of the 3rd Kind, but most peo­ple opt for the good old plas­tic box. Plas­tic box own­ers have prob­a­bly noticed though that box­es often begin to smell after six months or so due to plas­tic’s semi-porous nature and it can be hard to get off all residue, espe­cial­ly in scratched areas. That’s why it’s not uncom­mon to see peo­ple buy­ing a new plas­tic box every 6–8 months. But there is a bet­ter way!

Stain­less steel box­es exist and they are eas­i­er to clean, don’t suf­fer from odours, and help you avoid throw­ing more plas­tic out. Try the iPrim­io Ulti­mate Stain­less Steel Cat XL Lit­ter Box or the Yang­ba­ga stain­less steel cat lit­ter box.

Small bin for cat poop
There’s no need to auto­mat­i­cal­ly reach for the small bags that line your cat’s lit­ter box. Pour the lit­ter direct­ly into the box and just use one bag in a small, ded­i­cat­ed bin to clean up in your cat’s lit­ter box dai­ly. Depend­ing on the size of the bin, you should end up using few­er bags. 

Composting cat poop

First off, the gold­en rules: 

  • Cat poop com­post is not suit­able for grow­ing fruits and veg­eta­bles, so don’t mix cat poop with your reg­u­lar com­postable kitchen mate­ri­als 
  • Cat poop should not be sent to your com­mu­ni­ty com­post ser­vices (unless specif­i­cal­ly stat­ed that they offer such a ser­vice)

Oth­er than that if you have suit­able out­door space, set­ting up a ded­i­cat­ed cat poop com­post­ing area fol­lows many of the same rules as stan­dard com­post­ing. It does take longer and the poten­tial for unpleas­ant odours is greater though. 

P.S. Don’t for­get to use a com­postable cat lit­ter!  

Environmentally-friendly cat litters

Regard­less of which of these you choose, the best way to buy cat lit­ter is in bulk, fill­ing your own con­tain­er each time you go to the store. Unfor­tu­nate­ly far from all pet stores offer such a ser­vice, but they do exist. If you can’t find  a bulk option, then look for sim­ple paper pack­ag­ing and buy in large packs.   

1) Choose: Recycled paper

Recy­cled paper is a good biodegrad­able alter­na­tive to tra­di­tion­al lit­ters. There’s no dust, it’s absorbent, clumps rel­a­tive­ly well, and it’s light and easy to car­ry. How­ev­er, it will need to be changed reg­u­lar­ly.

2) Choose: Wood shavings

Com­plete­ly biodegrad­able, com­postable and with a pleas­ant, odour-mask­ing nat­ur­al aro­ma, if you can find them, wood shav­ings are a great choice for an eco-con­scious cat. This type of lit­ter may or may not clump, depend­ing on the form, e.g. pel­lets don’t clump well.

A package of Cat's Best litter
At EcoWolf, we’re fans of Cat’s Best, made from wood chips and pack­aged in paper.

3) Choose: Corn, wheat and grass

Corn-based lit­ter is biodegrad­able, absorbent, and con­trols odour. How­ev­er, corn aller­gy is one of the most com­mon aller­gies in cats. In addi­tion, it does tend to track a lot. 

Wheat lit­ter clumps, pro­vides odor con­trol, and is biodegrad­able.

Grass lit­ter is rel­a­tive­ly new on the scene, but it clumps, is biodegrad­able, and is light­weight. How­ev­er, it may not be as easy to find as oth­er biodegrad­able lit­ters.

Types of cat litter to avoid

1) Avoid: Clumping clay

Clump­ing and non-clump­ing clay cat lit­ters are cheap and ubiq­ui­tous. Their con­ve­nience how­ev­er masks an awk­ward envi­ron­men­tal truth: clump­ing clay is pro­duced from a nat­ur­al min­er­al called sodi­um ben­tonite, which is extract­ed from the ground in an envi­ron­men­tal­ly unfriend­ly process called strip min­ing. This involves clear­ing what­ev­er is on the sur­face of a min­ing site (trees, grass, plants, top­soil), dig­ging a hole and remov­ing the min­er­als. 

Need­less to say, strip min­ing is a high­ly destruc­tive process that tends to leave land bar­ren. Not only that, but clay lit­ter is non-biodegrad­able – just think of all the pot­tery lin­ing muse­um shelves – mean­ing that it will linger on in land­fill.   

Clay lit­ter is the plas­tic shop­ping bag of the lit­ter world.

Paws and Pines

There is also some anec­do­tal health con­cern due to the dust that accom­pa­nies clay lit­ter. There’s lit­tle hard proof, but some peo­ple asso­ciate inhala­tion of this dust with feline asth­ma. More wor­ry­ing though is that your cat could end up inad­ver­tent­ly ingest­ing the rem­nants of clump­ing lit­ter when they lick their paws, poten­tial­ly lead­ing to diges­tive block­ages as the clay expands upon con­tact with water.

Bot­tom line: Cheap but destruc­tive­ly mined and non-biodegrad­able, clay lit­ters are best avoid­ed.

What is clumping?

Clump­ing lit­ter expands when it comes into con­tact with water. This helps it to cre­ate sol­id clumps that are eas­i­er to scoop with­out hav­ing to throw out the whole lit­ter tray. Kit­tens espe­cial­ly some­times ingest lit­ter, so most vets rec­om­mend using non-clump­ing lit­ter until they’re at least three months old.

2) Avoid: Silica gel or “crystal” litter

This type of lit­ter is made from crys­talline sil­i­ca. It works in the same way as clay but is gen­er­al­ly more absorbent, mean­ing less of it poten­tial­ly gets thrown out. Nev­er­the­less, since it’s essen­tial­ly sand and that sticks around for a long time, we can’t real­ly call this type of lit­ter biodegrad­able in any mean­ing­ful way.

It’s also worth not­ing that, although defin­i­tive stud­ies are hard to come by, we know that the dust from crys­talline sil­i­ca is a car­cino­gen that has been linked to lung dis­ease and even can­cer in indus­tri­al work­ers.

Bot­tom line: More expen­sive than clay, eas­i­er to car­ry since it’s lighter, but not much bet­ter for the envi­ron­ment.

Kitty knows best: cat preferences

Litter type

A study by Dr. Peter Borchelt to inves­ti­gate feline lit­ter pref­er­ences found that fine-grained clump­ing lit­ter was used by cats twice as often as its near­est com­peti­tor. 

…an impor­tant fac­tor in cats’ pref­er­ence for lit­ter mate­r­i­al is its tex­ture, gran­u­lar­i­ty or coarse­ness […] a fine­ly tex­tured (clump­ing) clay, was pre­ferred to clay with larg­er par­ti­cle sizes.

Dr. Peter Borchelt

Whilst clay is clear­ly a bad option, know­ing that a fine, coarse mate­r­i­al is gen­er­al­ly more appeal­ing to cats should help you to select the best of the more eco-friend­ly options. 


Any­thing with a flo­ral or cit­rus scent should cer­tain­ly be avoid­ed. Many cats are also less than fond of odor con­trol addi­tives such as bak­ing soda or car­bon, which some com­mer­cial lit­ters con­tain.