Christchurch Bay is a resort beach at Barton on Sea on the south-west coast of Hampshire.
It looks out across Christchurch Bay with views of the Isle of Wight to the east.
The shingle beach has rock groynes and a steep slope, flattening to shallow sandy
flats that are exposed when the tide retreats. There are relatively stable paths along
the beach which is backed by 30 metre high clay cliffs.
Within the vicinity of the beach approximately 900 metres east, there is one storm
overflow called Becton Lane Barton on Sea storm overflow. Discharges occur when heavy
rainfall overwhelms the sewerage system but are designed not to affect bathing water
compliance.
Prior to 1997 treated effluent from Barton on Sea Sewage Treatment Works was disinfected
with hyper chlorite during summer periods and discharged via an outfall 1.5 km from
the bathing water sampling site. On rare occasions this might have affected bathing
water quality. This discharge ceased prior to the 1997 bathing season when flows were
diverted to Pennington Sewage Treatment Works to receive further treatment.
For the four year (2020-2023) assessment period where data is available, seaweed (macroalgae)
was assessed as being sufficient to be objectionable for 2% of visits, with 37% of
visits noting the presence of seaweed (macroalgae). This bathing water does not have
a history of large amounts of seaweed.
Modern sewerage systems have two separate systems, one takes foul sewage to sewage
treatment, the other takes rainwater runoff through surface water drains to rivers,
lakes and the sea. Misconnections occur when waste water pipes are plumbed into surface
water drains instead of the foul water sewerage system. This can give rise to pollution
when the waste water is discharged directly to the environment through the surface
water drain. For example, a washing machine or toilet may be incorrectly plumbed so
that it discharges to the surface drain rather than the foul sewage drain.
For the four year (2020-2023) assessment period where data is available, phytoplankton
(microscopic algae) was not assessed as being sufficient to be objectionable, but
was observed as being present on 2% of visits. Microscopic algae (phytoplankton) increase
in number at certain times of the year. This process is known as a phytoplankton bloom.
Blooms of phytoplankton can result in the water appearing discoloured or a foam forming
on the water.
The risks to human health from contact, ingestion or inhalation with marine algae
that currently occur in UK coastal waters are considered to be low. However, some
individuals may be more sensitive and display some reactions.
A common marine algae found in UK coastal waters is Phaeocystis, which is often mistaken
for sewage as it forms foam and a brown scum, but it is non-toxic.
There are no active pollution risk forecasts made at this bathing water. However any
bathing water has the potential to be affected by a pollution incident and if this
occurs a pollution risk warning with associated advice against bathing will be issued
on this website.
The Becton Bunny stream, which receives several storm overflow inputs, inputs 1.4
km east of the bathing water sampling site. Christchurch Harbour, which receives riverine
and other inputs, inputs 5.5 km to the west. These sources may contribute to a lower
standard of water quality after heavy rainfall.
Pennington Sewage Treatment Works discharges further treated sewage 9.5 km east the
bathing water and is designed to protect bathing water compliance. This discharge
was upgraded to receive ultraviolet disinfection to protect nearby shellfish beds
in 2013, which provides further protection to the bathing water. Christchurch Harbour,
which flows to sea 5.5 km west of the bathing water, receives further treated, ultraviolet
disinfected effluent from several sewage treatment works as well as inputs from storm
overflows. These discharges to Christchurch Harbour have been designed to have minimal
impact on bathing water compliance.
Environment Agency samplers make observations of litter present on the beach at every
visit, this includes assessments of sewage debris, litter and tar. At Christchurch
Bay for the four year (2020-2023) assessment period where data is available, sewage
debris was not noted at this site. Litter was not assessed as being sufficient to
be objectionable, but was observed as being present on 62% of visits. Tarry residue
was not noted at this site.
The natural drainage (hydrological) catchment surrounding the bathing water is approximately
450 hectares and drains into the Becton Bunny stream which discharges 1.4 km east
of the bathing water sampling site. The catchment is predominately urban, comprising
the town of Barton on Sea. Rainfall is drained from the town by a surface water drainage
network that discharges into the Becton Bunny stream. There are several storm overflow
discharges into the Becton Bunny stream.
Seaweed (macroalgae) and phytoplankton (microscopic algae) are a natural part of the
marine and freshwater environment. Below we note whether these have been recorded
in quantities sufficient to be a nuisance.
The majority of sewers in England are “combined sewers” and carry both sewage and
surface water from roofs and drains. A storm overflow operates during heavy rainfall
when the sewerage system becomes overwhelmed by the amount of surface water. The overflow
prevents sewage from backing up pipes and flooding properties and gardens. An emergency
overflow will only operate infrequently, for example due to pump failure or blockage
in the sewerage system.
Heavy rain falling on pavements and roads often flows into surface water drains or
highway drains, ending up in local rivers and ultimately the sea. The quality of bathing
water may be adversely affected as a result of such events.
It is the Environment Agency role to drive improvement of water quality at bathing
waters that are at risk of failing higher standards. It is natural for water to run
off the land to the sea. Water quality at a bathing water is dependent upon the type
and area of land (the catchment) draining to the water and the activities undertaken
in that catchment.