diff --git a/changelog.d/12336.misc b/changelog.d/12336.misc
new file mode 100644
index 000000000..0aecd543f
--- /dev/null
+++ b/changelog.d/12336.misc
@@ -0,0 +1 @@
+Remove the (broadly unused, dev-only) dockerfile for pg tests.
diff --git a/docker/Dockerfile-pgtests b/docker/Dockerfile-pgtests
deleted file mode 100644
index b94484ea7..000000000
--- a/docker/Dockerfile-pgtests
+++ /dev/null
@@ -1,30 +0,0 @@
-# Use the Sytest image that comes with a lot of the build dependencies
-# pre-installed
-FROM matrixdotorg/sytest:focal
-
-# The Sytest image doesn't come with python, so install that
-RUN apt-get update && apt-get -qq install -y python3 python3-dev python3-pip
-
-# We need tox to run the tests in run_pg_tests.sh
-RUN python3 -m pip install tox
-
-# Initialise the db
-RUN su -c '/usr/lib/postgresql/10/bin/initdb -D /var/lib/postgresql/data -E "UTF-8" --lc-collate="C.UTF-8" --lc-ctype="C.UTF-8" --username=postgres' postgres
-
-# Add a user with our UID and GID so that files get created on the host owned
-# by us, not root.
-ARG UID
-ARG GID
-RUN groupadd --gid $GID user
-RUN useradd --uid $UID --gid $GID --groups sudo --no-create-home user
-
-# Ensure we can start postgres by sudo-ing as the postgres user.
-RUN apt-get update && apt-get -qq install -y sudo
-RUN echo "user ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers
-
-ADD run_pg_tests.sh /run_pg_tests.sh
-# Use the "exec form" of ENTRYPOINT (https://docs.docker.com/engine/reference/builder/#entrypoint)
-# so that we can `docker run` this container and pass arguments to pg_tests.sh
-ENTRYPOINT ["/run_pg_tests.sh"]
-
-USER user
diff --git a/docker/run_pg_tests.sh b/docker/run_pg_tests.sh
deleted file mode 100755
index b22b6ef16..000000000
--- a/docker/run_pg_tests.sh
+++ /dev/null
@@ -1,19 +0,0 @@
-#!/usr/bin/env bash
-
-# This script runs the PostgreSQL tests inside a Docker container. It expects
-# the relevant source files to be mounted into /src (done automatically by the
-# caller script). It will set up the database, run it, and then use the tox
-# configuration to run the tests.
-
-set -e
-
-# Set PGUSER so Synapse's tests know what user to connect to the database with
-export PGUSER=postgres
-
-# Start the database
-sudo -u postgres /usr/lib/postgresql/10/bin/pg_ctl -w -D /var/lib/postgresql/data start
-
-# Run the tests
-cd /src
-export TRIAL_FLAGS="-j 4"
-tox --workdir=./.tox-pg-container -e py37-postgres "$@"
diff --git a/docs/development/contributing_guide.md b/docs/development/contributing_guide.md
index afa8766f8..9db9352c9 100644
--- a/docs/development/contributing_guide.md
+++ b/docs/development/contributing_guide.md
@@ -220,27 +220,6 @@ export SYNAPSE_POSTGRES_PASSWORD=mydevenvpassword
 trial
 ```
 
-#### Prebuilt container
-
-Since configuring PostgreSQL can be fiddly, we can make use of a pre-made
-Docker container to set up PostgreSQL and run our tests for us. To do so, run
-
-```shell
-scripts-dev/test_postgresql.sh
-```
-
-Any extra arguments to the script will be passed to `tox` and then to `trial`,
-so we can run a specific test in this container with e.g.
-
-```shell
-scripts-dev/test_postgresql.sh tests.replication.test_sharded_event_persister.EventPersisterShardTestCase
-```
-
-The container creates a folder in your Synapse checkout called
-`.tox-pg-container` and uses this as a tox environment. The output of any
-`trial` runs goes into `_trial_temp` in your synapse source directory — the same
-as running `trial` directly on your host machine.
-
 ## Run the integration tests ([Sytest](https://github.com/matrix-org/sytest)).
 
 The integration tests are a more comprehensive suite of tests. They
diff --git a/scripts-dev/test_postgresql.sh b/scripts-dev/test_postgresql.sh
deleted file mode 100755
index 43cfa256e..000000000
--- a/scripts-dev/test_postgresql.sh
+++ /dev/null
@@ -1,19 +0,0 @@
-#!/usr/bin/env bash
-
-# This script builds the Docker image to run the PostgreSQL tests, and then runs
-# the tests. It uses a dedicated tox environment so that we don't have to
-# rebuild it each time.
-
-# Command line arguments to this script are forwarded to "tox" and then to "trial".
-
-set -e
-
-# Build, and tag
-docker build docker/ \
-  --build-arg "UID=$(id -u)" \
-  --build-arg "GID=$(id -g)" \
-  -f docker/Dockerfile-pgtests \
-  -t synapsepgtests
-
-# Run, mounting the current directory into /src
-docker run --rm -it -v "$(pwd):/src" -v synapse-pg-test-tox:/tox synapsepgtests "$@"