Environment
Food waste disposers and the environment: numbers, history and what happens in Milan
This is not a "green" page. It is a page of numbers.
In short
Four numbers, before anything else.
How much electricity a disposer uses, how much water, where the scraps you send down the sink end up, and what independent studies found — including where the disposer does not do better than separate food waste collection. Every number has its source, listed at the bottom.
We start a long way off — the United States of the 1920s — and end up in your kitchen, in Milan and its province.
- Electricity
- About 1.4–1.6 kWh per person per year (University of Sheffield, 2026). For a family of three, little more than one euro a year at the ARERA reference tariff for Q3 2026 (an estimate, details below).
- Water
- Between 3 and 4 litres per person per day (the Sheffield study and the distributor's data sheet).
- Overall impact
- The most recent study (University of Sheffield, 2026) finds the disposer better than separate food waste collection on 14 environmental indicators out of 18, and worse on 4, climate change among them.
- In Milan
- Food waste is already collected well here. The disposer does not replace that collection: it works alongside it.
First things first
Wasting less comes before everything else.
In Italy each of us throws away about half a kilo of food a week: 554 grams (Waste Watcher, "Il caso Italia 2026"). No appliance solves that problem: it is solved by buying and storing food better.
What is left, though, is a share of scraps nobody can avoid: peels, cores, coffee grounds, eggshells, bones. This page is about those. It sets out where they can go and what changes if they leave through the sink instead of the bin.
Source: Waste Watcher International Observatory, "Il caso Italia 2026", 3 February 2026.
History and the world
An idea from 1927, and the cities that first banned it and then allowed it back.
An idea born in 1927 in a Wisconsin basement
The disposer was invented in 1927 by John W. Hammes, an architect from Racine, Wisconsin, working in his basement workshop. The patent came in 1935. In 1938 the company that makes it was founded, InSinkErator: 52 units left the workshop in the first year.
First banned, then allowed back: what happened in the cities
In the 1930s and 1940s many American cities banned sending food scraps into the sewer: the fear was that pipes would clog and treatment plants would be overloaded. Then, city after city, the bans were withdrawn on the strength of evidence collected in the field.
In the United States, according to the American Housing Survey, homes with a disposer went from about 40% (1985) to about 50% (2007).
- Jasper, Indiana (1947). After an outbreak linked to food waste fed to pigs, the mayor promoted a disposer in every home. By 1950, 800 homes out of 1,200 had one.
- New York (1997). The city lifted its ban after a 21-month municipal study.
- Philadelphia. A 2012-13 pilot project involved 175 homes: in the waste of the households taking part, food scraps fell by an average of 35%. Since 2016 a disposer has been compulsory in new residential buildings (Waste360, 13 January 2016).
The most studied case: Surahammar, Sweden
In Surahammar, Sweden, half the homes used a disposer for 15 years. The study published in 2010 in Water and Environment Journal found no significant effects on sewers or the treatment plant, with a single measurable difference: the plant produced 46% more biogas.
The reason: food scraps arriving at the plant can end up in the digesters, where bacteria turn them into biogas. The standard handbook for treatment plant designers says as much (Metcalf & Eddy, Wastewater Engineering, 5th edition, 2014): plants aiming to produce energy could encourage disposers.
Around the world, the choices are not all the same. In the United States the environmental agency (EPA), in its 2023 scale, places sending food scraps down the sewer among the least preferred options. In Sweden, since 2024, a disposer connected straight to the sewer no longer counts as separate food waste collection (it is still allowed when connected to a tank). The reason is always the same: the outcome depends on how the sewer network is built and on how the treatment plant works. It is also why Italian law ties the use of a disposer to a check by the operator, area by area.
Sources: U.S. EPA, Wasted Food Scale (2023); Stockholm Vatten och Avfall, rules for "avfallskvarn" (from 1 January 2024).
The most recent study
University of Sheffield, 2026: 18 indicators compared.
The most complete comparison available today is a University of Sheffield study published in May 2026 in the International Journal of Life Cycle Assessment. Over the full life cycle, it compares the disposer with kerbside food waste collection across 18 environmental indicators. Manufacturing data for the appliances was supplied by the manufacturer; the analysis is the authors' own.
Where the disposer does better (14 indicators out of 18)
For example particulate matter, ozone, ecotoxicity. What weighs most are the collection trucks and the bags, which are not needed for that share of scraps when there is a disposer.
Where it does worse (4 indicators out of 18)
| Indicator | Result for the disposer |
|---|---|
| Climate change | worse for the disposer |
| Acidification | worse |
| Carcinogenic toxicity | worse (linked to manufacturing materials) |
| Water consumption | worse |
On climate change the result depends on the treatment plant receiving the scraps and varies from plant to plant; the authors expect it to improve as plants reduce their losses. That is why we do not use climate as a selling point: see the note on sources at the foot of this page.
The authors also mention benefits they did not measure: less noise and truck traffic, no odours from storing waste at home, fewer rodents, no extra bin. And they point to the disposer as particularly suited to high-density apartment buildings.
Consumption
Electricity and water: the numbers.
- Electricity
- The Sheffield study calculates, for treating 100 kg of food scraps (roughly what one person produces in a year in the UK), 1.37 kWh with the entry models and 1.62 kWh with the advanced model. The Italian distributor's data sheet indicates about 3–4 kWh a year and motors from 375 to 450 W. The two figures are of the same order of magnitude.
- What it costs
- At the ARERA reference tariff for vulnerable customers under Maggior Tutela from 1 July 2026 — 31.63 cents per kWh, taxes included — one person's consumption is worth less than 50 cents a year; for a family of three, little more than one euro a year (€1.30–1.54). It is an estimate: your tariff may differ.
- Water: between 3 and 4 litres per person per day
- The Sheffield study calculates 1,299 litres per 100 kg of scraps, that is about 3.6 litres per person per day; the distributor's data sheet indicates less than 3 litres. Real consumption depends on how much food you process and how much water you let run.
- What it adds to the household
- In the typical British home, the study estimates an increase of about 0.2% in electricity consumption and 2% in water consumption.
Italy, today
What the law says, where food waste goes, what research says.
What Italian law says
Article 107(3) of Legislative Decree 152/2006, as amended in 2008, reads: "The disposal of waste into the sewer, even ground up, is not permitted, with the exception of organic waste from food scraps treated with food waste disposers that reduce it to fine particles, subject to the water service operator having ascertained the existence of a treatment system; the operator shall provide adequate information to the public, including a map of the areas served by such systems. Installation of the appliances is notified by the retailer to the water service operator, which monitors how widely they are used across its area." (Our translation; the Italian text is the one that counts.)
For us, when we install, that means two concrete things: before installing we check the area and the drain, and after installation we are the ones who notify the operator. For purchases with shipping the notification is the buyer's responsibility.
Why you still read "it's banned" online
Because before 2008 it was, and many pages have never been updated. On top of that, some municipal or building regulations may set rules of their own.
That is why we check your address: the rule that counts is the one from your operator and your building, not the one you find on a forum.
Where food waste goes in Italy
Organic waste is the most collected fraction of Italian separate collection: 37.4% of the total (ISPRA, Urban Waste Report 2025, 2024 data).
It is recovered mainly in integrated anaerobic/aerobic plants (58.5%), then through composting (34%) and through anaerobic digestion alone (7.5%).
The Italian food waste system works. The disposer does not replace it: it is a convenient alternative for part of the scraps, where the law allows it.
What Italian research says
A 2019 study by two Italian researchers — Franco Cecchi (University of Verona) and Cristina Cavinato (Ca' Foscari University of Venice), published in the International Journal of Environmental Research and Public Health — analysed the disposer as a final disposal route for food scraps. Their conclusions: less pollution linked to waste transport, lower running costs and greater energy recovery where the treatment plant has anaerobic digestion.
Between 2010 and 2011 there was also an Italian field trial, in Chieri (Turin), with the University of Verona, Politecnico di Torino and SMAT. We are not quoting its results until we have the publication in hand.
Municipalities that offer incentives
Some Italian municipalities grant a discount on the waste tax to those who install a disposer. One example: Portoferraio (Elba) provides a 30% reduction of the variable share of the TARI for homes with a disposer, subject to checks.
In the Milan area we are not aware of any such TARI reductions as at the date of this page.
Milan and its province
Milan already sorts its waste well. The disposer does not replace that.
Milan is one of the large cities with the highest separate collection rate: 63.0% in 2025 (provisional AMSA figure). Of organic waste alone, in 2025 the city collected 139,552 tonnes: about 102 kg per inhabitant, restaurants and businesses included.
Here food waste is already collected and treated. That is why, in Milan and its province, the disposer should not be presented as an alternative to collection: it is a complement, designed for the home kitchen.
- Fewer food waste bags under the sink, because the scraps the disposer can handle go straight down the drain.
- Fewer odours at home between one collection and the next.
- Collection continues: whatever the disposer does not handle — and all other waste — is sorted as always.
The two routes of a potato peel
As far as the sink the journey is the same. From there the route changes — not the fact that the peel gets treated.
From the bin
- Food waste bin
- Kerbside collection
- Treatment plant
From the sink
- Sink with a disposer
- Sewer
- Your municipality's treatment plant
Which plant receives your wastewater depends on the municipality: the selector below tells you.
Who runs the water service and the treatment plants
City of Milan: MM S.p.A.
Milan's treatment system is built around three plants — Nosedo, San Rocco and the consortium plant at Peschiera Borromeo — serving about 2.5 million population equivalent in total.
Municipalities of the metropolitan city: Gruppo CAP
Outside the city the integrated water service belongs to Gruppo CAP, which also runs most of the treatment plants. Which plant receives your wastewater depends on the area: the checker below tells you.
Environment
Check your area
Pick or type your municipality: we tell you who runs the water service and which plant receives the wastewater. It is not a yes or no on feasibility — that is established at the address, before installing.
These are the 133 municipalities of the Metropolitan City of Milan: Milan is served by MM S.p.A., the other municipalities by Gruppo CAP.
Sources: Gruppo CAP plant data sheets, MM S.p.A. public pages and the Metropolitan City water authority. Data updated on 19 September 2026.
Milan and its province
What happens to the scraps once they reach the plant
It depends on the plant, and we say so plainly.
- Nosedo (Milan)
- In 2026 MM announced an anaerobic digestion section, planned for the coming years, to produce biogas from sludge and recover energy. So today, at Nosedo, the scraps do not yet become biogas.
- Bresso–Niguarda (Gruppo CAP)
- The plant, which serves Bresso, Paderno Dugnano, Cinisello Balsamo, Cusano Milanino and Cormano, has an anaerobic sludge digestion line and produces biomethane fed into the gas grid.
- Your municipality
- Where the plant has anaerobic digestion, the scraps can contribute to biogas production — the effect measured at Surahammar. Where it does not, they are still treated along with the rest of the wastewater.
A story we already have here: San Felice di Segrate, early 1970s
In San Felice di Segrate, in the early 1970s, homes sold furnished came with an InSinkErator disposer as standard. Mr Puddu has lived there and used one ever since.
A particular case. Mr Puddu is an especially careful user: he uses the disposer as instructed and looks after it. The last one we installed for him, in 2009, is still running.
It is his case, tied to the way he uses and cares for it: not a promise about how long the product lasts.
What we do
- We check first
- Before installing we check the area and the drain, together with the technical checks under the sink.
- We install
- As plumbers, since 1977.
- We notify the operator of the installation
- As the law requires. You do not have to do anything: we take care of it.
Transparency
What we will not tell you (and why).
- That the disposer is "green" or "zero impact"
- No appliance is. We give you numbers, with their source.
- That it is a choice "for the climate"
- Studies on emissions give different results depending on the treatment plant. In the Sheffield study (2026) the disposer comes out worse on 4 indicators out of 18, climate change among them.
- That it "saves landfills"
- In Lombardy collected food waste does not go to landfill, and in Milan it is already collected and treated.
- That at your plant it will certainly become biogas
- It depends on the plant: we tell you address by address.
- That in Milan you are entitled to a TARI discount
- As things stand, we are not aware of one.
- How many years it will last
- Its life depends on use and maintenance; a promise would not be serious.
From 27 September 2026 generic environmental claims in advertising are prohibited by law. This page is written to respect that rule, one line at a time.
The history, year by year
From the 1935 patent to the 2026 study.
- 1927
John W. Hammes, an architect from Racine (Wisconsin), invents the disposer in his basement workshop
InSinkErator, company timeline
- 1935
The US patent is granted
InSinkErator, company timeline
- 1938
The manufacturer is founded: 52 units in the first year
InSinkErator, company timeline
- 1930s–40s
Many US cities ban food scraps in the sewer; the bans are later withdrawn
- 1947–1950
Jasper (Indiana): after an outbreak, a disposer in every home; 800 homes out of 1,200 by 1950
InSinkErator, company timeline
- Early 1970s
Local history
San Felice di Segrate: homes sold furnished with an InSinkErator disposer as standard
Mr Puddu's account and LantierImpianti
- 1985 → 2007
US homes with a disposer: from about 40% to about 50%
American Housing Survey (U.S. Census Bureau)
- 1997
New York lifts its ban after a 21-month municipal study
NYC Local Law 1997/071
- 2010
Surahammar (Sweden): 15 years with half the homes equipped; no significant effect on sewers or plant, +46% biogas
Evans et al., Water and Environment Journal
- 2010–2011
Chieri (Turin): field trial with the University of Verona, Politecnico di Torino and SMAT
Field project; results not quoted yet
- 2012–2013
Philadelphia, pilot on 175 homes: −35% food scraps in the bin
Waste360, 13 January 2016
- 2014
Metcalf & Eddy, Wastewater Engineering (5th ed.): energy-recovery plants could encourage disposers
Technical handbook
- 2016
Philadelphia makes disposers mandatory in new residential buildings
City of Philadelphia
- 2019
Cecchi & Cavinato (Verona, Venice): Italian study on disposers as a final disposal route
IJERPH 16(16):2860
- 2023
EPA (USA): in its 2023 scale, sending scraps down the sewer is among the least preferred options
U.S. EPA, Wasted Food Scale
- 2024
Sweden: a disposer connected straight to the sewer no longer counts as separate food waste collection
Stockholm Vatten och Avfall
- 2026
University of Sheffield: better than separate food waste collection on 14 indicators out of 18, worse on 4
Int. J. Life Cycle Assessment 31, art. 95
Sources
Every number, its source.
Where a figure is ours — a ratio, a division — we say so: "our calculation".
| Number or claim | Source | Type |
|---|---|---|
| 554 g of food thrown away per person per week, in Italy | Waste Watcher International Observatory, "Il caso Italia 2026", 3 February 2026 | Public (observatory) |
| 1.37 / 1.62 kWh per 100 kg; 1,299 L per 100 kg; +0.2% electricity, +2% water (UK home) | Ali, Atanasovska, Nichols, Speight, Koh — Int. J. Life Cycle Assessment 31, art. 95 (2026) (opens in a new tab) | Independent (manufacturing data from the manufacturer) |
| 14 indicators out of 18 better, 4 worse (climate change among them); high-density buildings | As above (2026) | Independent |
| "Between 3 and 4 litres per person per day" | Range between the Sheffield study (1,299 L / 365 ≈ 3.6 L, our calculation) and the distributor's data sheet (< 3 L) | Derived |
| 3–4 kWh a year; 375–450 W; < 3 L per person per day | Italian distributor's product data sheet | Manufacturer/distributor |
| 31.63 c€/kWh taxes included, from 1 July 2026 | ARERA, Maggior Tutela update, Q3 2026 (opens in a new tab) | Public |
| Costs in euro per year (less than 0.50 per person; 1.30–1.54 for three people) | Our calculation: Sheffield study consumption × ARERA tariff | Derived |
| 1927, 1935, 1938 (52 units); Jasper 1947–1950 | InSinkErator, company timeline (opens in a new tab) | Manufacturer |
| US homes with a disposer from ~40% to ~50% (1985–2007) | American Housing Survey (U.S. Census Bureau) | Public |
| New York, ban lifted after a 21-month study (1997) | NYC Local Law 1997/071 | Regulation |
| Surahammar: 15 years, half the homes, +46% biogas (2010) | Evans et al., Water and Environment Journal | Independent |
| Philadelphia: 175 homes, −35% food scraps in the bin (2012-13); mandatory in new buildings (2016) | Waste360, 13 January 2016; City of Philadelphia | Press / Legislation |
| EPA: sending scraps down the sewer among the least preferred options (2023) | U.S. EPA, Wasted Food Scale (opens in a new tab) | Public |
| Sweden: since 2024 a disposer connected straight to the sewer does not count as separate collection | Stockholm Vatten och Avfall, rules for "avfallskvarn" | Public (operator) |
| Energy-recovery plants could encourage disposers | Metcalf & Eddy, Wastewater Engineering, 5th ed. (2014) | Independent (handbook) |
| Wording of the sewer ban and of the exception for disposers; check by the operator; notification by the retailer | Article 107(3), Legislative Decree 152/2006, text in force (Gazzetta Ufficiale / Normattiva) | Legislation |
| Italian study: less transport, lower costs, energy recovery | Cecchi & Cavinato, IJERPH 16(16):2860 (2019) (opens in a new tab) | Independent |
| Chieri (Turin), 2010-2011: field trial with the University of Verona, Politecnico di Torino and SMAT | Field project; publication not yet obtained, results not quoted | To be obtained |
| Organic waste 37.4% of separate collection; recovery 58.5% integrated plants, 34% composting, 7.5% anaerobic digestion alone (2024 data) | ISPRA, Urban Waste Report 2025 | Public |
| Portoferraio: −30% of the variable TARI share | Municipality of Portoferraio, TARI desk | Public |
| Milan: separate collection 63.0% (2025, provisional); organic waste 139,552 t | AMSA, separate collection data (opens in a new tab) | Public (waste operator) |
| ~102 kg of organic waste per inhabitant (non-domestic users included) | Our calculation: 2025 AMSA data over residents at 1 January 2025 (Metropolitan City of Milan, ISTAT data) | Derived |
| Milan treatment system: three hubs (Nosedo, San Rocco, Peschiera Borromeo), ~2.5 million population equivalent | Integrated water service regulation of the City of Milan (MM), 2024 | Public (operator) |
| Nosedo: anaerobic digestion planned "in the coming years" | MM S.p.A., news of 23 June 2026 (opens in a new tab) | Public (operator) |
| Bresso–Niguarda: anaerobic digestion, biomethane into the grid, municipalities served | Gruppo CAP, public meeting of 12 November 2024 | Public (operator) |
| Operator and treatment plant by municipality ("Check your area" tool) | Gruppo CAP plant data sheets, MM S.p.A. public pages, Metropolitan City water authority | Public (operators) |
| San Felice di Segrate, early 1970s; a 2009 installation still running | Mr Puddu's account and LantierImpianti's direct experience | Testimony |
| Ban on generic environmental claims from 27 September 2026 | Legislative Decree 30 of 20 February 2026 (EU Dir. 2024/825) | Regulation |
Every figure on this page carries its source and its year. We do not present the disposer as a choice "for the climate": studies on emissions give different results depending on the treatment plant (University of Sheffield, 2026). We present it for what it is: a convenient, hygienic way of handling kitchen scraps, where the law allows it.
A LantierImpianti page. This is not an official InSinkErator page.
Data updated on 19 September 2026.
Want to know how things stand at your address?
We tell you which operator serves your area and which plant receives your wastewater. Then, if you have decided, we install and we notify the operator ourselves.